From 57f9ce2bbb85a263506953b49c3f69ee7a77c03d Mon Sep 17 00:00:00 2001 From: Kodjo Sossouvi Date: Sun, 9 Jul 2023 18:08:47 +0200 Subject: [PATCH] Fixed #20: I can parse simple concepts --- src/caching/BaseCache.py | 7 +- src/caching/DictionaryCache.py | 86 ++++- src/caching/FastCache.py | 39 +- src/caching/ListCache.py | 52 ++- src/caching/ListIfNeededCache.py | 9 +- src/common/utils.py | 3 + src/core/BuiltinConcepts.py | 2 + src/core/Sheerka.py | 16 - src/core/concept.py | 15 +- src/evaluators/DefConceptEvaluator.py | 26 +- src/evaluators/FilterSuccessful.py | 30 ++ src/evaluators/PythonParser.py | 8 + src/evaluators/RecognizeDefConcept.py | 2 +- src/evaluators/RecognizeSimpleConcept.py | 60 ++++ .../ResolvePythonVsSimpleConcept.py | 51 +++ src/evaluators/base_evaluator.py | 61 +++- src/ontologies/SheerkaOntologyManager.py | 15 +- src/parsers/ParserInput.py | 12 +- src/parsers/SimpleParserParser.py | 114 ++++++ src/parsers/parser_utils.py | 2 +- src/parsers/state_machine.py | 332 ++++++++++++++++++ src/services/SheerkaConceptEvaluator.py | 132 ++++++- src/services/SheerkaConceptManager.py | 149 +++++++- src/services/SheerkaDummyEventManager.py | 60 ++++ src/services/SheerkaPython.py | 39 +- tests/caching/test_DictionaryCache.py | 62 +++- tests/caching/test_FastCache.py | 39 ++ tests/caching/test_ListCache.py | 259 +++++++++++++- tests/caching/test_ListIfNeededCache.py | 13 +- tests/conftest.py | 9 +- tests/evaluators/test_DefConceptEvaluator.py | 13 + tests/evaluators/test_FilterSuccessful.py | 51 +++ .../evaluators/test_RecognizeSimpleConcept.py | 48 +++ .../test_ResolvePythonVsSimpleConcept.py | 57 +++ tests/helpers.py | 109 ++++++ tests/non_reg/test_non_reg1.py | 54 ++- ...ser.py => test_ConceptDefinitionParser.py} | 13 +- tests/parsers/test_SimpleConceptsParser.py | 142 ++++++++ tests/parsers/test_state_machine.py | 82 +++++ tests/services/test_ConceptEvaluator.py | 64 +++- tests/services/test_ConceptManager.py | 106 +++++- .../services/test_SheerkaDummyEventManager.py | 66 ++++ tests/services/test_SheerkaPython.py | 61 +++- tests/test_helpers.py | 41 ++- 44 files changed, 2462 insertions(+), 149 deletions(-) create mode 100644 src/evaluators/FilterSuccessful.py create mode 100644 src/evaluators/RecognizeSimpleConcept.py create mode 100644 src/evaluators/ResolvePythonVsSimpleConcept.py create mode 100644 src/parsers/SimpleParserParser.py create mode 100644 src/parsers/state_machine.py create mode 100644 src/services/SheerkaDummyEventManager.py create mode 100644 tests/evaluators/test_FilterSuccessful.py create mode 100644 tests/evaluators/test_RecognizeSimpleConcept.py create mode 100644 tests/evaluators/test_ResolvePythonVsSimpleConcept.py rename tests/parsers/{test_DefConceptParser.py => test_ConceptDefinitionParser.py} (98%) create mode 100644 tests/parsers/test_SimpleConceptsParser.py create mode 100644 tests/parsers/test_state_machine.py create mode 100644 tests/services/test_SheerkaDummyEventManager.py diff --git a/src/caching/BaseCache.py b/src/caching/BaseCache.py index 5430221..a5ee7f4 100644 --- a/src/caching/BaseCache.py +++ b/src/caching/BaseCache.py @@ -18,8 +18,9 @@ class BaseCache: self._max_size = max_size self._default = default # default value to return when key is not found. It can be a callable of key self._extend_exists = extend_exists # search in remote - self._alt_sdp_get = alt_sdp_get # How to get the value when called by alt_sdp - self._sdp = sdp # current instance of SheerkaDataProvider + self._sdp = sdp # How to get the value from the associated database (persisted values) + self._alt_sdp_get = alt_sdp_get # How to get the value when other ontologies + self._lock = RLock() self._current_size = 0 self._initialized_keys = set() # to keep the list of the keys already requested (using get()) @@ -88,7 +89,7 @@ class BaseCache: def disable_default(self): self._default = (lambda sdp, key: NotFound) if self._sdp else (lambda key: NotFound) - def put(self, key: str, value: object, alt_sdp=None): + def put(self, key: str | bool, value: object, alt_sdp=None): """ Add a new entry in cache :param key: diff --git a/src/caching/DictionaryCache.py b/src/caching/DictionaryCache.py index b6ddaac..44d9403 100644 --- a/src/caching/DictionaryCache.py +++ b/src/caching/DictionaryCache.py @@ -5,10 +5,20 @@ from common.global_symbols import NotFound class DictionaryCache(BaseCache): """ - Kind of all or nothing dictionary database - You can get the values key by by + It's a kind of 'all or nothing' dictionary database + You can get the values key by key But when you want to put, you must put the whole database For this reason, alt_sdp is not supported. The top ontology layer contains the whole database + >>> cache = DictionaryCache() + >>> cache.put(True, {"key1": "value1", "key2": "value2"}) # put the whole dictionary + >>> assert cache.copy() == {"key1": "value1", "key2": "value2"} + >>> assert cache.get("key1") == "value1" + + >>> cache.put(True, {"key3": "value3"}) + >>> assert cache.copy() == {"key1": "value1", "key2": "value2", "key3": "value3"} + + >>> cache.put(False, {"key4": "value4"}) + >>> assert cache.copy() == {"key4": "value4"} """ def auto_configure(self, cache_name): @@ -86,3 +96,75 @@ class DictionaryCache(BaseCache): self._current_size = 0 for v in self._cache.values(): self._current_size += len(v) if hasattr(v, "__len__") and not isinstance(v, str) else 1 + + def add_path(self, path: list, value): + """ + Us the path (list of string) to create a tree + the leaf of the tree is the list of all values which share the same path + :param path: + :type path: + :param value: + :type value: + :return: + :rtype: + """ + with self._lock: + current = self._cache + for item in path: + current.setdefault(item, {}) + current = current[item] + + current.setdefault("#values#", []).append(value) + self._current_size += 1 + + def remove_path(self, path: list, value): + """ + Remove a value, and its path if needed + :param path: + :type path: + :param value: + :type value: + :return: + :rtype: + """ + parents = [] + with self._lock: + current = self._cache + try: + for item in path: + parents.insert(0, current) + current = current[item] + + current["#values#"].remove(value) + self._current_size -= 1 + except (KeyError, ValueError): + pass + + if "#values#" in current: + # clean leaf + if len(current["#values#"]) == 0: + del current["#values#"] + + # clean tree + for item in parents: + to_remove = [k for k, v in item.items() if v == {}] + for k in to_remove: + del item[k] + + def get_from_path(self, path: list): + """ + Get the list of value that share the same path + :param path: + :type path: + :return: NotFound if the path does not exist + :rtype: + """ + with self._lock: + current = self._cache + try: + for item in path: + current = current[item] + + return current["#values#"] + except KeyError: + return NotFound diff --git a/src/caching/FastCache.py b/src/caching/FastCache.py index c8bdffc..6eeef09 100644 --- a/src/caching/FastCache.py +++ b/src/caching/FastCache.py @@ -12,6 +12,7 @@ class FastCache: self.lru = [] self.default = default self.calls = {} + self.restore_points = [] def __contains__(self, item): return self.has(item) @@ -35,6 +36,8 @@ class FastCache: self.cache[key] = value self.lru.append(key) self.calls[key] = 0 + if self.restore_points: + self.restore_points[0].append(key) def has(self, key): return key in self.cache @@ -52,6 +55,18 @@ class FastCache: return NotFound + def remove(self, key): + """ + Remove an entry + :param key: + :type key: + :return: + :rtype: + """ + self.lru.remove(key) + del self.cache[key] + del self.calls[key] + def evict_by_key(self, predicate): to_remove = [] @@ -60,12 +75,30 @@ class FastCache: to_remove.append(k) for k in to_remove: - self.lru.remove(k) - del self.cache[k] + self.remove(k) def copy(self): return self.cache.copy() def clear(self): self.cache.clear() - self.lru.clear() \ No newline at end of file + self.lru.clear() + self.restore_points.clear() + + def snapshot(self): + """ + From now on, all new added key will be recorded + :return: + :rtype: + """ + self.restore_points.insert(0, []) + + def revert_snapshot(self): + """ + All key recorded since the last snapshot will be removed + :return: + :rtype: + """ + if self.restore_points: + for key in self.restore_points.pop(0): + self.remove(key) diff --git a/src/caching/ListCache.py b/src/caching/ListCache.py index 0d174e6..db1bdbc 100644 --- a/src/caching/ListCache.py +++ b/src/caching/ListCache.py @@ -3,7 +3,6 @@ from common.global_symbols import NotFound, Removed from common.utils import sheerka_deepcopy - class ListCache(BaseCache): """ An in memory FIFO cache object @@ -13,7 +12,11 @@ class ListCache(BaseCache): def _put(self, key, value, alt_sdp): if key in self._cache: - self._cache[key].append(value) + if isinstance(self._cache[key], list): # to deal with the case when entry is Removed + self._cache[key].append(value) + else: + self._cache[key] = [value] + else: self._sync(key) @@ -63,4 +66,47 @@ class ListCache(BaseCache): if self._cache[new_key][i] == old_value: self._cache[new_key][i] = new_value # avoid add and remove in dict break # only the first one is affected - self._add_to_add(new_key) \ No newline at end of file + self._add_to_add(new_key) + + def _delete(self, key, value, alt_sdp): + if value is None: + if not self._is_cleared and alt_sdp and self._extend_exists(alt_sdp, key): + self._current_size += 1 - len(self._cache[key]) if key in self._cache else 1 + self._cache[key] = Removed + self._add_to_add(key) + else: + self._current_size -= len(self._cache[key]) + del self._cache[key] + self._add_to_remove(key) + + else: + try: + self._cache[key].remove(value) + if len(self._cache[key]) == 0: + if not self._is_cleared and alt_sdp and self._extend_exists(alt_sdp, key): + self._cache[key] = Removed + self._add_to_add(key) + # self._current_size -= 1 # Do not decrease size, as it's replaced by 'Removed' + else: + del self._cache[key] + self._add_to_remove(key) + self._current_size -= 1 + else: + self._add_to_add(key) + self._current_size -= 1 + except (KeyError, ValueError) as ex: + previous = self._alt_sdp_get(alt_sdp, key) if not self._is_cleared and alt_sdp else NotFound + if previous in (NotFound, Removed): + return True + + previous = sheerka_deepcopy(previous) + previous.remove(value) # will raise a ValueError if value is not in the set + if len(previous) == 0: + self._cache[key] = Removed + self._current_size += 1 + else: + self._cache[key] = previous + self._current_size += len(previous) + self._add_to_add(key) + + return True diff --git a/src/caching/ListIfNeededCache.py b/src/caching/ListIfNeededCache.py index f243280..1d003e0 100644 --- a/src/caching/ListIfNeededCache.py +++ b/src/caching/ListIfNeededCache.py @@ -99,10 +99,11 @@ class ListIfNeededCache(BaseCache): try: previous = self._cache[key] if isinstance(previous, list): - previous.remove(value) - self._cache[key] = previous[0] if len(previous) == 1 else previous - self._current_size -= 1 - self.to_add.add(key) + if value in previous: + previous.remove(value) + self._cache[key] = previous[0] if len(previous) == 1 else previous + self._current_size -= 1 + self.to_add.add(key) else: if previous == value: # I am about to delete the entry diff --git a/src/common/utils.py b/src/common/utils.py index 653d045..e1e7ada 100644 --- a/src/common/utils.py +++ b/src/common/utils.py @@ -163,6 +163,9 @@ def str_concept(t, drop_name=None, prefix="c:"): :param prefix: :return: """ + if t is None: + return "" + if isinstance(t, tuple): name, id_ = t[0], t[1] else: diff --git a/src/core/BuiltinConcepts.py b/src/core/BuiltinConcepts.py index 8990d9d..1fc2c20 100644 --- a/src/core/BuiltinConcepts.py +++ b/src/core/BuiltinConcepts.py @@ -3,9 +3,11 @@ class BuiltinConcepts: NEW_CONCEPT = "__NEW_CONCEPT" # when the definition of a new concept is added UNKNOWN_CONCEPT = "__UNKNOWN_CONCEPT" # Failed to find the requested concept + USER_INPUT = "__USER_INPUT" # user command PARSER_INPUT = "__PARSER_INPUT" # command that will be parsed PYTHON_CODE = "__PYTHON_CODE" # command that is parsed + PARSER_RESULT = "__PARSER_RESULT" # incomplete recognition of the concepts INVALID_CONCEPT = "__INVALID_CONCEPT" # failed to parse concept attributes EVALUATION_ERROR = "__EVALUATION_ERROR" # failed to evaluate concept diff --git a/src/core/Sheerka.py b/src/core/Sheerka.py index 57d9454..98f73c0 100644 --- a/src/core/Sheerka.py +++ b/src/core/Sheerka.py @@ -120,13 +120,11 @@ class Sheerka: # initialize_pickle_handlers() self.om = SheerkaOntologyManager(self, root_folder) - # self.builtin_cache, self.builtin_cache_by_class_name = self.get_builtins_classes_as_dict() self.initialize_bind_methods() self.initialize_caching() self.initialize_evaluators() self.initialize_services() - # self.initialize_builtin_evaluators() # self.om.init_subscriptions() event = Event("Initializing Sheerka.", user_id=self.name) @@ -269,20 +267,6 @@ class Sheerka: "config": self.config.__dict__ } - def publish(self, context, topic, data=None): - """ - To be removed as it must be part of the EventManager service - :param context: - :type context: - :param topic: - :type topic: - :param data: - :type data: - :return: - :rtype: - """ - pass - def evaluate_user_input(self, command: str, user: User): self.log.info("Processing '%s' from '%s'", command, user.email) diff --git a/src/core/concept.py b/src/core/concept.py index 9be821f..11e08e0 100644 --- a/src/core/concept.py +++ b/src/core/concept.py @@ -27,7 +27,12 @@ class DefinitionType: class ConceptMetadata: """ Static information of the Concept - + What is the difference between variable and parameter ? + A variable is an attribute of the concept + A parameter is a variable that must be set upon instantiation + for example : + def concept a plus b def_var a b => a and b are parameters (and also variables) + def concept color def_var color_name => color_name is a variable, but not a parameter """ id: str # unique identifier for a concept. The id will never be modified (but the key can) name: str @@ -45,8 +50,8 @@ class ConceptMetadata: autouse: bool # indicates if eval must be automatically called on the concept once validated bound_body: str # which property must be considered have default value for the concept props: dict # hashmap of properties, values - variables: tuple # list of concept variables(tuple), with their default values - parameters: tuple # list of variables that are part of the name of the concept + variables: list # list of concept variables(tuple), with their default values + parameters: set # variables that are part of the definition of the concept digest: str = None all_attrs: tuple = None @@ -138,7 +143,7 @@ class Concept: return True def __hash__(self): - return self._metadata.digest + return hash(self._metadata.digest) @property def id(self): @@ -198,5 +203,5 @@ class Concept: except AttributeError: return NotInit if name in self.all_attrs() else NotFound - def get_runtime_info(self): + def get_runtime_info(self) -> ConceptRuntimeInfo: return self._runtime_info diff --git a/src/evaluators/DefConceptEvaluator.py b/src/evaluators/DefConceptEvaluator.py index e81cc26..302404d 100644 --- a/src/evaluators/DefConceptEvaluator.py +++ b/src/evaluators/DefConceptEvaluator.py @@ -2,7 +2,7 @@ from common.global_symbols import NotInit from core.ExecutionContext import ContextActions, ExecutionContext from core.ReturnValue import ReturnValue from core.concept import DefinitionType -from core.error import ErrorContext, SheerkaException +from core.error import ErrorContext from evaluators.base_evaluator import EvaluatorEvalResult, EvaluatorMatchResult, OneReturnValueEvaluator from parsers.BnfDefinitionParser import BnfDefinitionParser from parsers.ConceptDefinitionParser import ConceptDefinition @@ -42,7 +42,7 @@ class DefConceptEvaluator(OneReturnValueEvaluator): try: concept_def = return_value.value variables = self._get_variables(context, concept_def) - parameters = None + parameters = {item[0] for item in variables} & set(self._get_possible_vars_from_def(context, concept_def)) if concept_def.definition_type == DefinitionType.BNF: self._validate_bnf(context, concept_def) @@ -76,10 +76,9 @@ class DefConceptEvaluator(OneReturnValueEvaluator): def _get_variables(self, context: ExecutionContext, concept_def: ConceptDefinition): variables_found = set() # list of names, there is no tuple - definition = concept_def.definition or concept_def.name - possible_vars_from_name = self._get_possible_vars_from_def(context, definition) + possible_parameters_from_name = self._get_possible_vars_from_def(context, concept_def) - possible_vars_from_name_as_set = set(possible_vars_from_name) + possible_parameters_from_name_as_set = set(possible_parameters_from_name) for part in CONCEPT_PARTS_TO_USE: # if these possibles variables are referenced in other parts of the definition, they may be variables part_value = getattr(concept_def, part) @@ -87,7 +86,7 @@ class DefConceptEvaluator(OneReturnValueEvaluator): continue possible_vars_from_part = self._get_possible_vars_from_part(context, part_value) - variables_found.update(possible_vars_from_name_as_set & possible_vars_from_part) + variables_found.update(possible_parameters_from_name_as_set & possible_vars_from_part) # add variables from add_var if concept_def.def_var: @@ -97,24 +96,31 @@ class DefConceptEvaluator(OneReturnValueEvaluator): # variables are sorted sorted_vars = [] - for possible_var in possible_vars_from_name: + for possible_var in possible_parameters_from_name: for found in with_default_value: if possible_var == found[0]: sorted_vars.append(found) + # force variables from def_var if they were filtered + variables_names = {item[0] for item in sorted_vars} + for item in with_default_value: + if item[0] not in variables_names: + sorted_vars.append(item) + return sorted_vars @staticmethod - def _get_possible_vars_from_def(context, definition): + def _get_possible_vars_from_def(context, concept_def: ConceptDefinition): """ :param context: :type context: - :param definition: - :type definition: + :param concept_def: + :type concept_def: :return: list of names :rtype: """ + definition = concept_def.definition or concept_def.name names = (str(t.value) for t in Tokenizer(definition) if t.type in NAMES_TOKEN_TYPES) possible_vars = filter(lambda x: not context.sheerka.is_a_concept_name(x), names) diff --git a/src/evaluators/FilterSuccessful.py b/src/evaluators/FilterSuccessful.py new file mode 100644 index 0000000..e4c3043 --- /dev/null +++ b/src/evaluators/FilterSuccessful.py @@ -0,0 +1,30 @@ +from core.ExecutionContext import ContextActions, ExecutionContext +from core.ReturnValue import ReturnValue +from evaluators.base_evaluator import AllReturnValuesEvaluator, EvaluatorEvalResult, EvaluatorMatchResult + + +class FilterSuccessful(AllReturnValuesEvaluator): + """ + When everything is evaluated, + removes all return values that not successful + """ + NAME = "FilterSuccessful" + + def __init__(self): + super().__init__(self.NAME, ContextActions.AFTER_EVALUATION, 80) + + def matches(self, context: ExecutionContext, return_values: list[ReturnValue]) -> EvaluatorMatchResult: + to_keep, to_drop = [], [] + for r in return_values: + if r.status: + to_keep.append(r) + else: + to_drop.append(r) + + return EvaluatorMatchResult(len(to_keep) > 0 and len(to_drop) > 0, + {"to_keep": to_keep, "to_drop": to_drop}) + + def eval(self, context: ExecutionContext, + evaluation_context: dict, + return_values: list[ReturnValue]) -> EvaluatorEvalResult: + return EvaluatorEvalResult(evaluation_context["to_keep"], evaluation_context["to_drop"]) diff --git a/src/evaluators/PythonParser.py b/src/evaluators/PythonParser.py index 6907c31..917f339 100644 --- a/src/evaluators/PythonParser.py +++ b/src/evaluators/PythonParser.py @@ -13,6 +13,10 @@ from parsers.tokenizer import TokenKind @dataclass() class PythonErrorNode(ErrorObj): + """ + Error object when failed to parse the source code + Contains the source code and the associated exception found when tried to compile + """ source: str exception: Exception @@ -30,6 +34,10 @@ class PythonErrorNode(ErrorObj): class PythonParser(OneReturnValueEvaluator): + """ + Tries to parse Python source code + Return Concept(PythonCode) with PythonFragment if python code is recognized + """ NAME = "PythonParser" def __init__(self): diff --git a/src/evaluators/RecognizeDefConcept.py b/src/evaluators/RecognizeDefConcept.py index f370f62..094244f 100644 --- a/src/evaluators/RecognizeDefConcept.py +++ b/src/evaluators/RecognizeDefConcept.py @@ -8,7 +8,7 @@ from parsers.ConceptDefinitionParser import ConceptDefinitionParser class RecognizeDefConcept(OneReturnValueEvaluator): """ - class the recognize input 'def concept [as ] [where ] [pre 
] [ret ]'
+    class that recognizes input 'def concept  [as ] [where ] [pre 
] [ret ]'
     """
     NAME = "RecognizeDefConcept"
 
diff --git a/src/evaluators/RecognizeSimpleConcept.py b/src/evaluators/RecognizeSimpleConcept.py
new file mode 100644
index 0000000..fb4d92a
--- /dev/null
+++ b/src/evaluators/RecognizeSimpleConcept.py
@@ -0,0 +1,60 @@
+from core.BuiltinConcepts import BuiltinConcepts
+from core.ExecutionContext import ContextActions, ExecutionContext
+from core.ReturnValue import ReturnValue
+from core.concept import Concept
+from evaluators.base_evaluator import EvaluatorEvalResult, EvaluatorMatchResult, NotForMe, OneReturnValueEvaluator
+from parsers.SimpleParserParser import SimpleConceptsParser
+from parsers.state_machine import MetadataToken
+
+
+class RecognizeSimpleConcept(OneReturnValueEvaluator):
+    """
+    class that recognizes concepts in the input
+    It only focuses on concepts thot do not require parameter
+    """
+    NAME = "RecognizeSimpleConcept"
+
+    def __init__(self):
+        super().__init__(self.NAME, ContextActions.PARSING, 80)
+        self.parser = SimpleConceptsParser()
+
+    def matches(self, context: ExecutionContext, return_value: ReturnValue) -> EvaluatorMatchResult:
+        return EvaluatorMatchResult(return_value.status and
+                                    context.sheerka.isinstance(return_value.value, BuiltinConcepts.PARSER_INPUT))
+
+    def eval(self, context: ExecutionContext,
+             evaluation_context: object,
+             return_value: ReturnValue) -> EvaluatorEvalResult:
+        parser_input = return_value.value.body
+        parser_input.reset()
+
+        parsed = self.parser.parse(context, parser_input)
+
+        if len(parsed.items) == 0:
+            not_for_me = ReturnValue(self.NAME, False, NotForMe(self.NAME, return_value.value))
+            return EvaluatorEvalResult([not_for_me], [])
+
+        new = []
+        for sequence in parsed.items:
+            instantiated = []
+            has_unrecognized = False
+            for item in sequence:
+                # instantiate the concept
+                if isinstance(item, MetadataToken):
+                    concept = context.sheerka.newi(item.metadata.id)
+                    concept.get_runtime_info().info["resolution_method"] = item.resolution_method
+                    instantiated.append(concept)
+                else:
+                    instantiated.append(item.buffer)
+                    has_unrecognized = True
+
+            if has_unrecognized:
+                parser_result = context.sheerka.newn(BuiltinConcepts.PARSER_RESULT, result=instantiated)
+                new.append(ReturnValue(self.NAME, False, parser_result, [return_value]))
+            else:
+                # remove whitespaces first
+                instantiated = [item for item in instantiated if isinstance(item, Concept) or not item.isspace()]
+                to_return = instantiated[0] if len(instantiated) == 1 else instantiated
+                new.append(ReturnValue(self.NAME, True, to_return, [return_value]))
+
+        return EvaluatorEvalResult(new, [return_value])
diff --git a/src/evaluators/ResolvePythonVsSimpleConcept.py b/src/evaluators/ResolvePythonVsSimpleConcept.py
new file mode 100644
index 0000000..39dbe78
--- /dev/null
+++ b/src/evaluators/ResolvePythonVsSimpleConcept.py
@@ -0,0 +1,51 @@
+from core.ExecutionContext import ContextActions, ExecutionContext
+from core.ReturnValue import ReturnValue
+from evaluators.PythonParser import PythonParser
+from evaluators.RecognizeSimpleConcept import RecognizeSimpleConcept
+from evaluators.base_evaluator import AllReturnValuesEvaluator, EvaluatorEvalResult, EvaluatorMatchResult
+
+
+class ResolvePythonVsSimpleConcept(AllReturnValuesEvaluator):
+    """
+    A one long name concept can be recognized by PythonParser the SimpleConceptParser
+    The evaluator resolves the conflict when it's the case
+    The rule is simple by the way, always prefer the SimpleConceptParser
+    """
+
+    NAME = "ResolvePythonVsSimpleConcept"
+
+    def __init__(self):
+        super().__init__(self.NAME, ContextActions.AFTER_PARSING, 90)
+
+    def matches(self, context: ExecutionContext, return_values: list[ReturnValue]) -> EvaluatorMatchResult:
+        """
+        Browse the return values
+        if both PythonParser and RecognizeSimpleConcept are successful, we must choose one
+        :param context:
+        :type context:
+        :param return_values:
+        :type return_values:
+        :return:
+        :rtype:
+        """
+        to_keep = None
+        to_drop = None
+        others = []
+        for ret_val in return_values:
+            if ret_val.status and ret_val.who == PythonParser.NAME:
+                to_drop = ret_val
+            elif ret_val.status and ret_val.who == RecognizeSimpleConcept.NAME:
+                to_keep = ret_val
+            else:
+                others.append(ret_val)
+
+        if to_keep and to_drop:
+            return EvaluatorMatchResult(True, {"to_keep": to_keep, "to_drop": to_drop, "others": others})
+
+        return EvaluatorMatchResult(False)
+
+    def eval(self, context: ExecutionContext,
+             evaluation_context: dict,
+             return_values: list[ReturnValue]) -> EvaluatorEvalResult:
+        return EvaluatorEvalResult([evaluation_context["to_keep"]] + evaluation_context["others"],
+                                   [evaluation_context["to_drop"]])
diff --git a/src/evaluators/base_evaluator.py b/src/evaluators/base_evaluator.py
index 2e2cfc8..63e9571 100644
--- a/src/evaluators/base_evaluator.py
+++ b/src/evaluators/base_evaluator.py
@@ -1,13 +1,15 @@
 from dataclasses import dataclass
+from typing import Any
 
-from core.ExecutionContext import ExecutionContext, ContextActions
+from core.ExecutionContext import ContextActions, ExecutionContext
 from core.ReturnValue import ReturnValue
+from core.error import ErrorObj
 
 
 @dataclass
 class EvaluatorMatchResult:
     status: bool
-    obj: object = None
+    obj: dict = None
 
 
 @dataclass
@@ -48,12 +50,11 @@ class OneReturnValueEvaluator(BaseEvaluator):
     Evaluate one specific return value
     """
 
-    def matches(self, context: ExecutionContext,
-                return_value: ReturnValue) -> EvaluatorMatchResult:
+    def matches(self, context: ExecutionContext, return_value: ReturnValue) -> EvaluatorMatchResult:
         pass
 
     def eval(self, context: ExecutionContext,
-             evaluation_context: object,
+             evaluation_context: dict,
              return_value: ReturnValue) -> EvaluatorEvalResult:
         pass
 
@@ -63,11 +64,55 @@ class AllReturnValuesEvaluator(BaseEvaluator):
     Evaluates the groups of ReturnValues
     """
 
-    def matches(self, context: ExecutionContext,
-                return_values: list[ReturnValue]) -> EvaluatorMatchResult:
+    def matches(self, context: ExecutionContext, return_values: list[ReturnValue]) -> EvaluatorMatchResult:
         pass
 
     def eval(self, context: ExecutionContext,
-             evaluation_context: object,
+             evaluation_context: dict,
              return_values: list[ReturnValue]) -> EvaluatorEvalResult:
         pass
+
+
+class MultipleChoices:
+    def __init__(self, items: list):
+        self.items = items
+
+    def __iter__(self):
+        return iter(self.items)
+
+    def __len__(self):
+        return len(self.items)
+
+    def __repr__(self):
+        if self.items:
+            return f"MultipleChoices({', '.join([repr(item) for item in self.items])})"
+        else:
+            return f"MultipleChoices( **empty** )"
+
+    def __eq__(self, other):
+        if not isinstance(other, MultipleChoices):
+            return False
+
+        if len(other.items) != len(self.items):
+            return False
+
+        for _self, _other in zip(self.items, other.items):
+            if _self != _other:
+                return False
+
+        return True
+
+    def __hash__(self):
+        return hash(tuple(self.items))
+
+
+@dataclass
+class NotForMe(ErrorObj):
+    """
+    Return by an Evaluator are execution if the input was not for it
+    """
+    who: str  # who issued the NotForMe
+    items: Any  # ReturnValue value(s)
+
+    def get_error_msg(self) -> str:
+        return f"{self.items} is not for '{self.who}'"
diff --git a/src/ontologies/SheerkaOntologyManager.py b/src/ontologies/SheerkaOntologyManager.py
index 0b41b0c..198a323 100644
--- a/src/ontologies/SheerkaOntologyManager.py
+++ b/src/ontologies/SheerkaOntologyManager.py
@@ -3,9 +3,8 @@ from caching.CacheManager import CacheManager
 from caching.DictionaryCache import DictionaryCache
 from caching.FastCache import FastCache
 from caching.SetCache import SetCache
-from common.global_symbols import EVENT_CONCEPT_ID_DELETED, \
-    EVENT_RULE_ID_DELETED, NotFound, \
-    Removed
+from common.global_symbols import EVENT_CONCEPT_ID_DELETED, EVENT_ONTOLOGY_CREATED, EVENT_ONTOLOGY_DELETED, \
+    EVENT_RULE_ID_DELETED, NotFound, Removed
 from ontologies.Exceptions import OntologyAlreadyExists, OntologyManagerCannotPopLatest, OntologyManagerFrozen, \
     OntologyManagerNotFrozen, OntologyNotFound
 from sdp.sheerkaDataProvider import SheerkaDataProvider
@@ -84,7 +83,7 @@ class Ontology:
 class SheerkaOntologyManager:
     ROOT_ONTOLOGY_NAME = "__default__"
     SELF_CACHE_MANAGER = "__ontology_manager__"  # cache to store SheerkaOntologyManager info
-    CONCEPTS_BY_ONTOLOGY_ENTRY = "ConceptsByOntologyEntry"
+    CONCEPTS_BY_ONTOLOGY_ENTRY = "ConceptsByOntologyEntry"  # stores concepts id created in ontologies
     RULES_BY_ONTOLOGY_ENTRY = "RulesByOntologyEntry"
     ONTOLOGY_BY_CONCEPT_ENTRY = "OntologyByConceptEntry"
     ONTOLOGY_BY_RULE_ENTRY = "OntologyByRuleEntry"
@@ -156,7 +155,6 @@ class SheerkaOntologyManager:
         """
         Add an ontology layer
         :param name: name of the layer
-        :param cache_only:
         """
         if not self.frozen:
             raise OntologyManagerNotFrozen()
@@ -178,6 +176,8 @@ class SheerkaOntologyManager:
         alt_sdp = AlternateSdp(self.ontologies)
         new_ontology = Ontology(name, len(self.ontologies), cache_manager, alt_sdp)
         self.ontologies.insert(0, new_ontology)
+
+        self.sheerka.publish(None, EVENT_ONTOLOGY_CREATED, new_ontology)
         return new_ontology
 
     def pop_ontology(self, context):
@@ -206,7 +206,9 @@ class SheerkaOntologyManager:
                 self.internal_cache_manager.delete(self.ONTOLOGY_BY_RULE_ENTRY, rule)
             self.internal_cache_manager.delete(self.RULES_BY_ONTOLOGY_ENTRY, ontology_name)
 
-        return self.ontologies.pop(0)
+        ontology = self.ontologies.pop(0)
+        self.sheerka.publish(context, EVENT_ONTOLOGY_DELETED, ontology)
+        return ontology
 
     def add_ontology(self, ontology: Ontology):
         """
@@ -221,6 +223,7 @@ class SheerkaOntologyManager:
         for cache_def in ontology.cache_manager.caches.values():
             cache_def.cache.reset_initialized_keys()
 
+        self.sheerka.publish(None, EVENT_ONTOLOGY_CREATED, ontology)
         return self
 
     def revert_ontology(self, context, ontology) -> Ontology:
diff --git a/src/parsers/ParserInput.py b/src/parsers/ParserInput.py
index f89037a..611d029 100644
--- a/src/parsers/ParserInput.py
+++ b/src/parsers/ParserInput.py
@@ -75,7 +75,7 @@ class ParserInput:
                     return self.all_tokens[-1]
 
         return self.all_tokens[my_pos]
-    
+
     def seek(self, pos):
         """
         Move the token offset to position pos
@@ -90,5 +90,15 @@ class ParserInput:
         self.token = self.all_tokens[self.pos]
         return True
 
+    def clone(self):
+        res = ParserInput(self.original_text)
+        res.all_tokens = self.all_tokens
+        res.exception = self.exception
+        res.pos = self.pos
+        res.end = self.end
+        res.token = self.token
+
+        return res
+
     def __repr__(self):
         return f"ParserInput('{self.original_text}', len={len(self.all_tokens)})"
diff --git a/src/parsers/SimpleParserParser.py b/src/parsers/SimpleParserParser.py
new file mode 100644
index 0000000..296331b
--- /dev/null
+++ b/src/parsers/SimpleParserParser.py
@@ -0,0 +1,114 @@
+from core.concept import DefinitionType
+from evaluators.base_evaluator import MultipleChoices
+from parsers.state_machine import ConceptToRecognize, End, ManageUnrecognized, MetadataToken, PrepareReadTokens, \
+    ReadConcept, ReadTokens, Start, StateMachine, StateMachineContext, UnrecognizedToken
+from parsers.tokenizer import Token, TokenKind, Tokenizer
+
+
+class SimpleConceptsParser:
+    """"
+    This class to parser concepts with no variable
+    It parses a sequence of concepts
+    """
+
+    def __init__(self):
+        tokens_wkf = {
+            Start("start", next_states=["prepare read tokens"]),
+            PrepareReadTokens("prepare read tokens", next_states=["read tokens"]),
+            ReadTokens("read tokens", next_states=["read tokens", "eof", "concepts found"]),
+            ManageUnrecognized("eof", next_states=["end"]),
+            ManageUnrecognized("concepts found", next_states=["#concept_wkf"]),
+            End("end", next_states=None)
+        }
+
+        concept_wkf = {
+            Start("start", next_states=["read concept"]),
+            ReadConcept("read concept", next_states=["#tokens_wkf"]),
+        }
+
+        self.workflows = {
+            "#tokens_wkf": {t.name: t for t in tokens_wkf},
+            "#concept_wkf": {t.name: t for t in concept_wkf},
+        }
+        self.error_sink = []
+
+    @staticmethod
+    def get_metadata_from_first_token(context, token: Token):
+        def _get_expected_tokens(_metadata, attr):
+            return [t.strip_quote for t in Tokenizer(getattr(_metadata, attr), yield_eof=False)][1:]
+
+        if token.type == TokenKind.CONCEPT:
+            name, concept_id = token.value
+            if concept_id:
+                return [ConceptToRecognize(context.sheerka.get_by_id(concept_id), [], "id")]
+            else:
+                metadata = context.sheerka.get_by_name(name)
+                return [ConceptToRecognize(metadata, [], "name")] if not isinstance(metadata, list) else \
+                    [ConceptToRecognize(m, [], "name") for m in metadata]
+
+        concepts_by_key = [ConceptToRecognize(m, _get_expected_tokens(m, "key"), "key")
+                           for m in context.sheerka.get_metadatas_from_first_token("key", token.value)
+                           if m.definition_type == DefinitionType.DEFAULT and len(m.parameters) == 0]
+
+        concepts_by_name = [ConceptToRecognize(m, _get_expected_tokens(m, "name"), "name")
+                            for m in context.sheerka.get_metadatas_from_first_token("name", token.value)]
+
+        return concepts_by_key + concepts_by_name
+
+    def parse(self, context, parser_input):
+        sm = StateMachine(self.workflows)
+        sm_context = StateMachineContext(context, parser_input, self.get_metadata_from_first_token)
+        sm.run("#tokens_wkf", "start", sm_context)
+
+        selected = self.select_best_paths(sm)
+
+        return MultipleChoices(selected)
+
+    def select_best_paths(self, sm):
+        """
+        Returns a list of sequence
+        :param sm:
+        :type sm:
+        :return:
+        :rtype:
+        """
+        selected = []
+        best_score = 1
+        for path in sm.paths:
+            if path.execution_context.errors:
+                continue
+
+            score = self._compute_path_score(path)
+
+            if score > best_score:
+                selected.clear()
+                selected.append(path.execution_context.result)
+                best_score = score
+            elif score == best_score:
+                selected.append(path.execution_context.result)
+        return selected
+
+    @staticmethod
+    def _compute_path_score(path):
+        """
+        To compute the score of a path
+        We look at the MetadataToken, that represent the concepts that are recognized
+        The first idea was to look at the concepts that use the maximum of token in a row
+        example :
+        Concept("I am a concept") is better than Concept("I am") + Unrecognized(" a concept")
+
+        but :
+        Concept("one two") should be equivalent to Concept("one") followed by Concept("two")
+        :param path:
+        :type path:
+        :return:
+        :rtype:
+        """
+        score = 0
+        for token in path.execution_context.result:
+            if isinstance(token, MetadataToken):
+                score += token.end - token.start + 1
+            elif isinstance(token, UnrecognizedToken) and token.buffer.isspace():
+                score += len(token.buffer)
+
+        return score
diff --git a/src/parsers/parser_utils.py b/src/parsers/parser_utils.py
index cec1b03..9e1ce11 100644
--- a/src/parsers/parser_utils.py
+++ b/src/parsers/parser_utils.py
@@ -83,7 +83,7 @@ class KeywordNotFound(ErrorObj):
 
 @dataclass()
 class UnexpectedEof(ErrorObj):
-    keyword: str
+    keyword: str  # expected keyword or token
     last_token: Token | None
 
     def get_error_msg(self):
diff --git a/src/parsers/state_machine.py b/src/parsers/state_machine.py
new file mode 100644
index 0000000..fcec99e
--- /dev/null
+++ b/src/parsers/state_machine.py
@@ -0,0 +1,332 @@
+from dataclasses import dataclass, field
+from typing import Any, Literal
+
+from common.utils import str_concept
+from core.ExecutionContext import ExecutionContext
+from core.concept import ConceptMetadata
+from parsers.ParserInput import ParserInput
+from parsers.parser_utils import UnexpectedEof, UnexpectedToken, get_text_from_tokens
+from parsers.tokenizer import Token
+
+
+@dataclass
+class MetadataToken:
+    """
+    Class that represents a text that is recognized as a concept
+    We keep track of the start and the end position
+    """
+    metadata: ConceptMetadata
+    start: int
+    end: int
+    resolution_method: Literal["name", "key", "id"]
+    parser: str
+
+    def __repr__(self):
+        return f"(MetadataToken metadata={str_concept(self.metadata, drop_name=True)}, " + \
+            f"start={self.start}, end={self.end}, method={self.resolution_method}, origin={self.parser})"
+
+    def __eq__(self, other):
+        if not isinstance(other, MetadataToken):
+            return False
+
+        return self.metadata.id == other.metadata.id \
+            and self.start == other.start \
+            and self.end == other.end \
+            and self.parser == other.parser
+
+    def __hash__(self):
+        return hash((self.metadata.id, self.start, self.end, self.parser))
+
+
+@dataclass
+class UnrecognizedToken:
+    """
+    Class that represents a text that is not recognized
+    We keep track of the start and the end position
+    """
+    buffer: str
+    start: int
+    end: int
+
+
+@dataclass
+class StateResult:
+    next_state: str | None
+    forks: list = None
+
+
+@dataclass
+class ConceptToRecognize:
+    """
+    Holds information about the concept to recognize
+    """
+    metadata: ConceptMetadata
+    expected_tokens: list
+    resolution_method: Literal["name", "key", "id"]  # which attribute was used to resolve the concept
+
+
+@dataclass
+class StateMachineContext:
+    context: ExecutionContext
+    parser_input: ParserInput
+    get_metadata_from_first_token: Any
+    buffer: list[Token] = field(default_factory=list)
+    buffer_start_pos: int = -1
+    concept_to_recognize: ConceptToRecognize | None = None
+    result: list = field(default_factory=list)
+    errors: list = field(default_factory=list)
+
+    def get_clones(self, concepts_to_recognize):
+        return [StateMachineContext(self.context,
+                                    self.parser_input.clone(),
+                                    self.get_metadata_from_first_token,
+                                    self.buffer.copy(),
+                                    self.buffer_start_pos,
+                                    concept,
+                                    self.result.copy(),
+                                    self.errors.copy())
+                for concept in concepts_to_recognize]
+
+    def to_debug(self):
+        return {"pos": self.parser_input.pos,
+                "token": self.parser_input.token,
+                "buffer": [token.value for token in self.buffer],
+                "concept": str_concept(self.concept_to_recognize.metadata) if self.concept_to_recognize else None,
+                "result": self.result.copy()}
+
+
+class State:
+    def __init__(self, name, next_states):
+        self.name = name
+        self.next_states = next_states
+
+    def run(self, state_context: StateMachineContext) -> StateResult:
+        pass
+
+    @staticmethod
+    def get_forks(next_state, states_contexts: list[StateMachineContext]):
+        """
+        Create on fork item for every state context
+        :param next_state:
+        :type next_state:
+        :param states_contexts:
+        :type states_contexts:
+        :return:
+        :rtype:
+        """
+        return [(next_state, state_context) for state_context in states_contexts]
+
+    def __repr__(self):
+        return f"(State '{self.name}' -> {self.next_states})"
+
+
+class Start(State):
+    def run(self, state_context) -> StateResult:
+        # Start state
+        # give some logs and ask for the next state
+        return StateResult(self.next_states[0])
+
+    def __repr__(self):
+        return f"(StartState '{self.name}' -> '{self.next_states[0]}')"
+
+
+class PrepareReadTokens(State):
+    def run(self, state_context: StateMachineContext) -> StateResult:
+        state_context.buffer.clear()
+        state_context.buffer_start_pos = state_context.parser_input.pos + 1
+        return StateResult(self.next_states[0])
+
+
+class ReadTokens(State):
+    def run(self, state_context) -> StateResult:
+        if not state_context.parser_input.next_token(False):
+            return StateResult("eof")
+
+        # try to get the possible concepts to recognize
+        concepts = state_context.get_metadata_from_first_token(state_context.context,
+                                                               state_context.parser_input.token)
+
+        forks = self.get_forks("concepts found", state_context.get_clones(concepts)) if concepts else None
+
+        state_context.buffer.append(state_context.parser_input.token)
+        return StateResult(self.name, forks)
+
+
+class ManageUnrecognized(State):
+    def run(self, state_context) -> StateResult:
+        if state_context.buffer:
+            buffer_as_str = get_text_from_tokens(state_context.buffer)
+            if len(state_context.result) > 0 and isinstance(old := state_context.result[-1], UnrecognizedToken):
+                state_context.result[-1] = UnrecognizedToken(old.buffer + buffer_as_str,
+                                                             old.start,
+                                                             state_context.parser_input.pos - 1)
+            else:
+                state_context.result.append(UnrecognizedToken(buffer_as_str,
+                                                              state_context.buffer_start_pos,
+                                                              state_context.parser_input.pos - 1))
+
+        return StateResult(self.next_states[0])
+
+
+class ReadConcept(State):
+    def run(self, state_context) -> StateResult:
+        start = state_context.parser_input.pos
+
+        for expected in state_context.concept_to_recognize.expected_tokens:
+            if not state_context.parser_input.next_token(False):
+                # eof before the concept is recognized
+                state_context.errors.append(UnexpectedEof(expected, state_context.parser_input.token))
+                state_context.concept_to_recognize = None
+                return StateResult(self.next_states[0])
+
+            token = state_context.parser_input.token
+            if token.value != expected:
+                # token mismatch
+                state_context.errors.append(UnexpectedToken(token, expected))
+                state_context.concept_to_recognize = None
+                return StateResult(self.next_states[0])
+
+        state_context.result.append(MetadataToken(state_context.concept_to_recognize.metadata,
+                                                  start,
+                                                  state_context.parser_input.pos,
+                                                  state_context.concept_to_recognize.resolution_method,
+                                                  "simple"))
+
+        state_context.concept_to_recognize = None
+        return StateResult(self.next_states[0])
+
+
+class End(State):
+    def run(self, state_context) -> StateResult:
+        return StateResult(None)
+
+    def __repr__(self):
+        return f"(EndState '{self.name}')"
+
+
+@dataclass
+class ExecutionPathHistory:
+    from_state: str
+    execution_context_debug: dict
+    to_state: str = ""
+    forks: list[tuple] = None
+    parents: list = None
+
+    def clone(self, parent_path_id):
+        parents = self.parents.copy() if self.parents else []
+        parents.append(parent_path_id)
+        return ExecutionPathHistory(self.from_state,
+                                    self.execution_context_debug.copy(),
+                                    self.to_state,
+                                    self.forks.copy() if self.forks else None,
+                                    parents)
+
+    def __repr__(self):
+        return "History(from '{0}', to '{1}', using {2}, forks={3}, parents={4}".format(
+            self.from_state,
+            self.to_state,
+            self.execution_context_debug,
+            len(self.forks) if self.forks else 0,
+            self.parents)
+
+
+@dataclass
+class ExecutionPath:
+    path_id: int
+    execution_context: Any
+    current_workflow: str
+    current_state: str
+
+    history: list[ExecutionPathHistory]
+    ended: bool = False
+
+    def clone(self, path_id, new_execution_path, new_workflow, new_state):
+        return ExecutionPath(path_id,
+                             new_execution_path,
+                             new_workflow,
+                             new_state,
+                             [h.clone(self.path_id) for h in self.history],
+                             self.ended)
+
+    def __repr__(self):
+        return f"(Path id={self.path_id}, workflow='{self.current_workflow}', state='{self.current_state}')"
+
+    def get_audit_trail(self):
+        return [h.from_state for h in self.history]
+
+
+class StateMachine:
+
+    def __init__(self, workflows):
+        self.workflows = workflows
+        self.paths = None
+        self.last_path_id = -1
+
+    def run(self, workflow_name: str, state_name: str, execution_context):
+        """
+        Run the workflow from the state given in parameter
+        :param workflow_name:
+        :type workflow_name:
+        :param state_name:
+        :type state_name:
+        :param execution_context:
+        :type execution_context:
+        :return:
+        :rtype:
+        """
+        self.last_path_id = -1  # reset the path ids
+        self.paths = [ExecutionPath(self._get_new_path_id(),
+                                    execution_context,
+                                    workflow_name,
+                                    state_name,
+                                    [],
+                                    False)]
+
+        while True:
+            to_review = [p for p in self.paths if not p.ended]
+            if len(to_review) == 0:
+                break
+
+            for path in to_review:
+                # add traceability
+                history = ExecutionPathHistory(f"{path.current_workflow}:{path.current_state}",
+                                               path.execution_context.to_debug())
+                path.history.append(history)
+
+                current_state = self.workflows[path.current_workflow][path.current_state]
+                res = current_state.run(path.execution_context)
+
+                if res.next_state is None:
+                    path.ended = True
+                    continue  # not possible to fork !
+
+                path.current_workflow, path.current_state = self._compute_next_workflow_and_state(path.current_workflow,
+                                                                                                  res.next_state)
+
+                # update traceability
+                history.to_state = f"{path.current_workflow}:{path.current_state}"
+
+                # add forks
+                if res.forks:
+                    new_paths = []
+                    for next_state, next_execution_context in res.forks:
+                        next_workflow, next_state = self._compute_next_workflow_and_state(path.current_workflow,
+                                                                                          next_state)
+                        new_paths.append(path.clone(self._get_new_path_id(),
+                                                    next_execution_context,
+                                                    next_workflow,
+                                                    next_state))
+
+                    self.paths.extend(new_paths)
+                    history.forks = [p.path_id for p in new_paths]
+
+    def _get_new_path_id(self):
+        self.last_path_id += 1
+        return self.last_path_id
+
+    @staticmethod
+    def _compute_next_workflow_and_state(workflow, state):
+        if state.startswith("#"):
+            return state, "start"
+        else:
+            return workflow, state
diff --git a/src/services/SheerkaConceptEvaluator.py b/src/services/SheerkaConceptEvaluator.py
index c704cdd..3aaf4b1 100644
--- a/src/services/SheerkaConceptEvaluator.py
+++ b/src/services/SheerkaConceptEvaluator.py
@@ -1,20 +1,22 @@
+import ast
 from dataclasses import dataclass
 
 from caching.FastCache import FastCache
 from common.ast_utils import WhereConstraintVisitor
-from common.global_symbols import CustomType, NotFound, NotInit
+from common.global_symbols import CustomType, EVENT_ONTOLOGY_CREATED, EVENT_ONTOLOGY_DELETED, NotFound, NotInit
 from core.BuiltinConcepts import BuiltinConcepts
 from core.ExecutionContext import ContextActions, ExecutionContext
 from core.ReturnValue import ReturnValue
 from core.concept import Concept, ConceptDefaultProps, ConceptDefaultPropsAttrs, ConceptMetadata
-from core.error import ErrorObj, SheerkaException
+from core.error import ErrorConcepts, ErrorObj, SheerkaException
 from core.python_fragment import PythonFragment
 from services.BaseService import BaseService
-from services.SheerkaPython import EvalMethod, EvaluationContext, EvaluationRef, MultipleResults
+from services.SheerkaPython import ConceptRef, EvalMethod, EvaluationContext, MultipleResults, ObjectRef
 
 PARSING_STEPS = [
     ContextActions.BEFORE_PARSING,
     ContextActions.PARSING,
+    ContextActions.AFTER_PARSING,
 ]
 
 CONDITIONAL_ATTR = [ConceptDefaultProps.WHERE, ConceptDefaultProps.PRE]
@@ -48,6 +50,14 @@ class PredicateIsFalse(ErrorObj):
         return f"Failed to match condition '{self.predicate}' with namespace {self.namespace}."
 
 
+class ConceptEvalError(ErrorObj):
+    def __init__(self, message):
+        self.message = message
+
+    def get_error_msg(self) -> str:
+        return self.message
+
+
 @dataclass
 class InfiniteRecursion(ErrorObj):
     """
@@ -56,6 +66,19 @@ class InfiniteRecursion(ErrorObj):
     ids: list
 
 
+@dataclass
+class TooManySuccess(ErrorObj):
+    values: list
+
+
+@dataclass
+class TooManyErrors(ErrorObj):
+    values: list
+
+    def get_error_msg(self) -> str:
+        return "\n".join([e.get_error_msg() for e in self.values])
+
+
 @dataclass
 class PredicateIsTrue:
     """
@@ -78,12 +101,16 @@ class ConceptEvaluator(BaseService):
 
     def __init__(self, sheerka):
         super().__init__(sheerka)
-        self.compiled_cache = FastCache()
-        self.where_constraints_cache = FastCache(default=None)
+        self.compiled_cache = FastCache(max_size=2048)
+        self.where_constraints_cache = FastCache(max_size=2048)
 
     def initialize(self):
         self.sheerka.bind_service_method(self.NAME, self.evaluate_concept, True)
 
+    def initialize_deferred(self, context, first_time):
+        self.sheerka.subscribe(EVENT_ONTOLOGY_CREATED, self._on_ontology_created)
+        self.sheerka.subscribe(EVENT_ONTOLOGY_DELETED, self._on_ontology_removed)
+
     def evaluate_concept(self, context: ExecutionContext,
                          concept: Concept,
                          hints: ConceptEvaluationHints = None):
@@ -141,11 +168,20 @@ class ConceptEvaluator(BaseService):
         compiled = ConceptCompiled()
         with context.push(self.NAME, ContextActions.BUILD_CONCEPT, {"metadata": action_context}) as sub_context:
 
+            variables = {k for k, v in metadata.variables}
+
             for attr, source_code in action_context.items():
                 if source_code is None or source_code == "":
                     setattr(compiled, attr, None)
                     continue
 
+                if source_code in variables:
+                    # Reference to internal variable
+                    python_fragment = self._ensure_python_fragment(context, source_code)
+                    setattr(compiled, attr, python_fragment)
+                    continue
+
+                # else, we need to parse the source code
                 with sub_context.push(self.NAME, ContextActions.BUILD_CONCEPT_ATTR, {"attr": attr}) as attr_context:
                     start = ReturnValue(self.NAME,
                                         True,
@@ -156,15 +192,17 @@ class ConceptEvaluator(BaseService):
                     ret = sheerka.execute(attr_context, [start], PARSING_STEPS)
                     attr_context.add_values(return_values=ret)
 
-                    value = ret[0].value
+                    only_successful = self._only_one_successful(ret)
+                    value = self._ensure_python_fragment(context, only_successful)
+
                     if isinstance(value, ErrorObj):
                         setattr(compiled, attr, value)
                         compiled.errors[attr] = value.get_error_msg()
                     else:
                         # Add reference to internal variables
-                        python_fragment = value.pf
+                        python_fragment = value
                         for k, v in metadata.variables:
-                            python_fragment.namespace[k] = EvaluationRef("self", k)
+                            python_fragment.namespace[k] = ObjectRef("self", k)
 
                         setattr(compiled, attr, python_fragment)
 
@@ -225,10 +263,8 @@ class ConceptEvaluator(BaseService):
                     if (attr_constraints := self._get_where_constraints(concept, attr)) is not None:
                         res = self._apply_attr_constraints(context, attr_constraints, attr, res)
 
-                    if isinstance(res, ErrorObj):
+                    if isinstance(res, ErrorObj) or isinstance(res, Concept) and res.name in ErrorConcepts:
                         errors[attr] = res
-                        concept.set_value(attr, NotInit)
-                        res = NotInit
 
                     concept.set_value(attr, res)
 
@@ -244,20 +280,84 @@ class ConceptEvaluator(BaseService):
 
         concept.get_runtime_info().is_evaluated = True
 
-        if errors:
+        if context.sheerka.isinstance(error_in_body := concept.body, BuiltinConcepts.EVALUATION_ERROR):
+            # if the body is an 'EVALUATION_ERROR', it needs to be propagated.
+            # There is no need to create a new EVALUATION_ERROR concept
+            concept.get_runtime_info().error = error_in_body.reason
+            return error_in_body
+        elif errors:
+            # if some new errors are detected, We must return an EVALUATION_ERROR concept
             error_concept = sheerka.newn(BuiltinConcepts.EVALUATION_ERROR, concept=concept, reason=errors)
             concept.get_runtime_info().error = errors
             return error_concept
-        elif context.sheerka.isinstance(error_in_body := concept.body, BuiltinConcepts.EVALUATION_ERROR):
-            # if the body is an 'evaluation_error', it needs to be propagated
-            concept.get_runtime_info().error = error_in_body.reason
-            return error_in_body
 
         if (ret := concept.get_value(ConceptDefaultProps.RET)) is NotInit:
             return concept
         else:
             return ret
 
+    def _on_ontology_created(self, context, ontology):
+        self.compiled_cache.snapshot()
+        self.where_constraints_cache.snapshot()
+
+    def _on_ontology_removed(self, context, ontology):
+        self.compiled_cache.revert_snapshot()
+        self.where_constraints_cache.revert_snapshot()
+
+    @staticmethod
+    def _ensure_python_fragment(context, obj) -> PythonFragment | ErrorObj:
+        """
+        We can evaluate only python code
+        Concepts found must be transformed into python fragment of code
+        The python fragment will be an identifier
+          and the real value of the concept will be stored in the namespace of the PythonFragment
+        :param obj:
+        :type obj:
+        :return:
+        :rtype:
+        """
+        if isinstance(obj, (ErrorObj, PythonFragment)):
+            return obj
+
+        if context.sheerka.isinstance(obj, BuiltinConcepts.PYTHON_CODE):
+            return obj.pf
+
+        if isinstance(obj, (Concept, MultipleResults)):
+            concept_ref = f"__REF__{id(obj)}"
+            ast_tree = ast.parse(concept_ref, "", 'eval')
+            ref = ConceptRef(obj) if isinstance(obj, Concept) else MultipleResults(*(ConceptRef(o) for o in obj.items))
+            return PythonFragment(concept_ref, ast_tree=ast_tree, namespace={concept_ref: ref})
+
+        if isinstance(obj, str):
+            ast_tree = ast.parse(obj, "", 'eval')
+            return PythonFragment(obj, ast_tree=ast_tree, namespace={obj: ObjectRef("self", obj)})
+
+        return ConceptEvalError(f"Cannot process intput '{obj}'")
+
+    @staticmethod
+    def _only_one_successful(return_values):
+        """
+        After parsing the source code, we may found multiple possible results
+        First, disqualify all failed return values.
+        Return MultipleResult if we cannot found out which one to choose
+        :param return_values:
+        :type return_values:
+        :return:
+        :rtype:
+        """
+        if len(return_values) == 1:
+            return return_values[0].value
+
+        only_successful = [r for r in return_values if r.status]
+        if len(only_successful) == 1:
+            return only_successful[0].value
+
+        if len(only_successful) > 1:
+            # TODO:  make sure those are concepts !
+            return MultipleResults(*(r.value for r in only_successful))
+
+        return TooManyErrors([r.value for r in return_values])
+
     @staticmethod
     def _detect_recursion(context, current_concept_id):
         ids = []
diff --git a/src/services/SheerkaConceptManager.py b/src/services/SheerkaConceptManager.py
index 964edbd..92f3ec7 100644
--- a/src/services/SheerkaConceptManager.py
+++ b/src/services/SheerkaConceptManager.py
@@ -1,9 +1,11 @@
 import hashlib
 import logging
 from dataclasses import dataclass
+from typing import Literal
 
 from caching.Cache import Cache
 from caching.FastCache import FastCache
+from caching.ListCache import ListCache
 from caching.ListIfNeededCache import ListIfNeededCache
 from common.global_symbols import NotFound, NotInit, VARIABLE_PREFIX
 from common.utils import get_logger_name, unstr_concept
@@ -41,10 +43,24 @@ class InvalidBnf(ErrorObj):
 
 
 @dataclass
-class FirstItemError(ErrorObj):
+class NoFirstItemError(ErrorObj):
     pass
 
 
+@dataclass
+class ConceptRef:
+    concept: Concept
+
+    def __eq__(self, other):
+        if not isinstance(other, ConceptRef):
+            return False
+
+        return self.concept.id == other.concept.id
+
+    def __hash__(self):
+        return hash(self.concept.id)
+
+
 class ConceptManager(BaseService):
     """
     The service is used for the administration of concepts
@@ -60,7 +76,10 @@ class ConceptManager(BaseService):
     CONCEPTS_BY_ID_ENTRY = "ConceptManager:Concepts_By_ID"  # to store all the concepts
     CONCEPTS_BY_KEY_ENTRY = "ConceptManager:Concepts_By_Key"
     CONCEPTS_BY_NAME_ENTRY = "ConceptManager:Concepts_By_Name"
-    CONCEPTS_BY_HASH_ENTRY = "ConceptManager:Concepts_By_Hash"  # sto
+    CONCEPTS_BY_HASH_ENTRY = "ConceptManager:Concepts_By_Hash"
+
+    CONCEPT_BY_FIRST_TOKEN_IN_KEY = "ConceptManager:Concepts_By_First_Token_In_Key"
+    CONCEPT_BY_FIRST_TOKEN_IN_NAME = "ConceptManager:Concepts_By_First_Token_In_Name"
 
     def __init__(self, sheerka):
         super().__init__(sheerka, order=11)
@@ -78,7 +97,9 @@ class ConceptManager(BaseService):
         self.sheerka.bind_service_method(self.NAME, self.get_by_name, False)
         self.sheerka.bind_service_method(self.NAME, self.get_by_id, False)
         self.sheerka.bind_service_method(self.NAME, self.get_by_key, False)
+        self.sheerka.bind_service_method(self.NAME, self.get_by_digest, False)
         self.sheerka.bind_service_method(self.NAME, self.is_a_concept_name, False)
+        self.sheerka.bind_service_method(self.NAME, self.get_metadatas_from_first_token, False)
 
         register_concept_cache = self.sheerka.om.register_concept_cache
 
@@ -95,6 +116,12 @@ class ConceptManager(BaseService):
         cache = ListIfNeededCache().auto_configure(self.CONCEPTS_BY_HASH_ENTRY)
         register_concept_cache(self.CONCEPTS_BY_HASH_ENTRY, cache, lambda c: c.digest, True)
 
+        cache = ListCache().auto_configure(self.CONCEPT_BY_FIRST_TOKEN_IN_KEY)
+        self.sheerka.om.register_cache(self.CONCEPT_BY_FIRST_TOKEN_IN_KEY, cache)
+
+        cache = ListCache().auto_configure(self.CONCEPT_BY_FIRST_TOKEN_IN_NAME)
+        self.sheerka.om.register_cache(self.CONCEPT_BY_FIRST_TOKEN_IN_NAME, cache)
+
     def initialize_deferred(self, context, is_first_time):
         if is_first_time:
             self.sheerka.om.put(self.sheerka.OBJECTS_IDS_ENTRY, self.USER_CONCEPTS_IDS, 1000)
@@ -102,12 +129,13 @@ class ConceptManager(BaseService):
             _ = self._create_builtin_concept
             _(1, BuiltinConcepts.SHEERKA, desc="Sheerka")
             _(2, BuiltinConcepts.NEW_CONCEPT, desc="On new concept creation", variables=("metadata",))
-            _(3, BuiltinConcepts.UNKNOWN_CONCEPT, desc="Unknown concept", variables=("requested_name", "requested_id"))
+            _(3, BuiltinConcepts.UNKNOWN_CONCEPT, desc="Unknown concept", variables=("requested",))
             _(4, BuiltinConcepts.USER_INPUT, desc="Any external input", variables=("command",))
             _(5, BuiltinConcepts.PARSER_INPUT, desc="tokenized input", variables=("pi",))
             _(6, BuiltinConcepts.PYTHON_CODE, desc="python code", variables=("pf",))  # pf for PythonFragment
-            _(7, BuiltinConcepts.INVALID_CONCEPT, desc="invalid concept", variables=("concept_id", "reason"))
-            _(8, BuiltinConcepts.EVALUATION_ERROR, desc="evaluation error", variables=("concept", "reason"))
+            _(7, BuiltinConcepts.PARSER_RESULT, desc="parser result", variables=("result",))
+            _(8, BuiltinConcepts.INVALID_CONCEPT, desc="invalid concept", variables=("concept_id", "reason"))
+            _(9, BuiltinConcepts.EVALUATION_ERROR, desc="evaluation error", variables=("concept", "reason"))
 
             self.init_log.debug('%s builtin concepts created',
                                 len(self.sheerka.om.current_cache_manager().concept_caches))
@@ -129,7 +157,7 @@ class ConceptManager(BaseService):
                            desc: str = "",  # possible description for the concept
                            props: dict = None,  # hashmap of default properties
                            variables: list = None,  # list of concept variables(tuple), with their default values
-                           parameters: list = None  # list of variables that are part of the name of the concept
+                           parameters: set = None  # list of variables that are part of the name of the concept
                            ) -> ReturnValue:
         """
         Adds the definition of a new concept
@@ -151,14 +179,13 @@ class ConceptManager(BaseService):
             post,
             ret,
             definition,
-            definition_type,
+            DefinitionType.DEFAULT if definition_type is None else definition_type,
             desc,
             autouse,
             bound_body,
-            props or {},
-            variables or (),
-            parameters or (),
-        )
+            {} if props is None else props,
+            [] if variables is None else variables,
+            set() if parameters is None else parameters)
 
         digest = self.compute_metadata_digest(metadata)
         if self.sheerka.om.exists_in_current(self.CONCEPTS_BY_HASH_ENTRY, digest):
@@ -177,15 +204,28 @@ class ConceptManager(BaseService):
         #         error = ErrorContext(self.NAME, context, ex)
         #         return ReturnValue(self.NAME, False, error)
 
-        # try:
-        #     first_item_res = self.recompute_first_items(context, None, [metadata])
-        # except FirstItemError as ex:
-        #     return ReturnValue(self.NAME, False, ex)
+        first_token_by_key = self._get_concept_first_token(concept_key)
+        if first_token_by_key is None:
+            return ReturnValue(self.NAME, False, self.newn(BuiltinConcepts.INVALID_CONCEPT,
+                                                           concept_id=concept_id,
+                                                           reason=NoFirstItemError()))
+
+        first_token_by_name = self._get_concept_first_token(name)
+        if first_token_by_name is None:
+            return ReturnValue(self.NAME, False, self.newn(BuiltinConcepts.INVALID_CONCEPT,
+                                                           concept_id=concept_id,
+                                                           reason=NoFirstItemError()))
 
         # at this point everything is fine. let's get the id and save everything
         om = self.sheerka.om
         metadata.id = str(self.sheerka.om.get(self.sheerka.OBJECTS_IDS_ENTRY, self.USER_CONCEPTS_IDS))
         om.add_concept(metadata)
+
+        # add the first token to the
+        om.put(self.CONCEPT_BY_FIRST_TOKEN_IN_KEY, first_token_by_key, metadata.id)
+        if first_token_by_name != first_token_by_key:
+            om.put(self.CONCEPT_BY_FIRST_TOKEN_IN_NAME, first_token_by_name, metadata.id)
+
         # self.update_first_items_caches(context, first_item_res)
         # if bnf_expr:
         #     self.bnf_expr_cache.put(metadata.id, bnf_expr)
@@ -208,7 +248,7 @@ class ConceptManager(BaseService):
         """
         metadata = self.get_by_name(concept_name)
         if metadata is NotFound:
-            return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested_name=concept_name)
+            return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested=concept_name)
 
         if isinstance(metadata, list):
             return [self._inner_new(m, **kwargs) for m in metadata]
@@ -228,7 +268,7 @@ class ConceptManager(BaseService):
         """
         metadata = self.get_by_id(concept_id)
         if metadata is NotFound:
-            return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested_id=concept_id)
+            return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested=f"#{concept_id}")
         return self._inner_new(metadata, **kwargs)
 
     def new(self, identifier, **kwargs):
@@ -244,6 +284,29 @@ class ConceptManager(BaseService):
         if isinstance(identifier, (ConceptMetadata, Concept)):
             return self._inner_new(identifier.get_metadata(), **kwargs)
 
+        if isinstance(identifier, ConceptRef):
+            # first, try the digest
+            resolved_identifier = identifier.concept.get_definition_digest()
+            metadata = self.get_by_digest(resolved_identifier)
+            if metadata is NotFound:
+                # used the same method that was used when the concept was first recognized
+                match identifier.concept.get_runtime_info().info["resolution_method"]:
+                    case "id":
+                        resolved_identifier = f"#{identifier.concept.id}"
+                        metadata = self.get_by_id(resolved_identifier)
+                    case "key":
+                        resolved_identifier = identifier.concept.key
+                        metadata = self.get_by_key(resolved_identifier)
+                    case _:
+                        resolved_identifier = identifier.concept.name
+                        metadata = self.get_by_name(resolved_identifier)
+
+            if metadata is NotFound:
+                return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested=resolved_identifier)
+            else:
+                return [self.new(item, **kwargs) for item in metadata] if \
+                    isinstance(metadata, list) else self._inner_new(metadata, **kwargs)
+
         if isinstance(identifier, list):
             return [self.new(item, **kwargs) for item in identifier]
 
@@ -257,7 +320,8 @@ class ConceptManager(BaseService):
         if isinstance(identifier, str):
             return self.newn(identifier, **kwargs)
 
-        return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested_name=identifier)
+        # failed to instantiate the concept
+        return self._inner_new(self.get_by_name(BuiltinConcepts.UNKNOWN_CONCEPT), requested=identifier)
 
     def get_by_name(self, key: str):
         """
@@ -289,9 +353,36 @@ class ConceptManager(BaseService):
         """
         return self.sheerka.om.get(self.CONCEPTS_BY_KEY_ENTRY, key)
 
+    def get_by_digest(self, digest: str):
+        """
+        Returns a concept metadata, using its digest
+        :param digest:
+        :type digest:
+        :return: NotFound if not found
+        :rtype:
+        """
+        return self.sheerka.om.get(self.CONCEPTS_BY_HASH_ENTRY, digest)
+
     def get_all_concepts(self):
         return list(sorted(self.sheerka.om.list(self.CONCEPTS_BY_ID_ENTRY), key=lambda item: int(item.id)))
 
+    def get_metadatas_from_first_token(self, attr: Literal["key", "name"], token: str):
+        """
+        Get the list of the concepts that start with token
+        :param attr: "key" or "name"
+        :type attr:
+        :param token:
+        :type token:
+        :return:
+        :rtype:
+        """
+        cache_name = self.CONCEPT_BY_FIRST_TOKEN_IN_NAME if attr == "name" else self.CONCEPT_BY_FIRST_TOKEN_IN_KEY
+        concepts_ids = self.sheerka.om.get(cache_name, token)
+        if concepts_ids is NotFound:
+            return []
+
+        return [self.get_by_id(c_id) for c_id in concepts_ids]
+
     def is_a_concept_name(self, name):
         return self.sheerka.om.exists(self.CONCEPTS_BY_NAME_ENTRY, name)
 
@@ -385,6 +476,28 @@ class ConceptManager(BaseService):
         metadata.all_attrs = self.compute_all_attrs(variables_to_use)
         self.sheerka.om.add_concept(metadata)
 
+    @staticmethod
+    def _get_concept_first_token(concept_key):
+        """
+        Return the list of tokens that consist of the first par of a concept key
+        >>> assert _get_concept_first_token("I am a concept") == "I"
+        >>> assert _get_concept_first_token("__var__1 multiplied by __var__2") == "multiplied"
+        :param concept_key: 
+        :type concept_key: 
+        :return: 
+        :rtype: 
+        """
+        keywords = concept_key.split()
+        # trim first variables
+        res = []
+        for keyword in keywords:
+            if keyword.startswith(VARIABLE_PREFIX):
+                continue
+
+            return keyword
+
+        return None
+
     @staticmethod
     def _inner_new(_metadata_def: ConceptMetadata, **kwargs):
         concept = Concept(_metadata_def)
diff --git a/src/services/SheerkaDummyEventManager.py b/src/services/SheerkaDummyEventManager.py
new file mode 100644
index 0000000..9401103
--- /dev/null
+++ b/src/services/SheerkaDummyEventManager.py
@@ -0,0 +1,60 @@
+from multiprocessing import RLock
+
+from services.BaseService import BaseService
+
+
+class SheerkaDummyEventManager(BaseService):
+    """
+    Manage simple publish and subscribe functions
+    Need to be replaced by a standard in the industry (Redis?)
+    """
+    NAME = "DummyEventManager"
+
+    def __init__(self, sheerka):
+        super().__init__(sheerka, order=2)
+        self._lock = RLock()
+        self.subscribers = {}
+
+    def initialize(self):
+        self.sheerka.bind_service_method(self.NAME, self.subscribe, True, visible=False)
+        self.sheerka.bind_service_method(self.NAME, self.publish, True, visible=False)
+
+    def subscribe(self, topic, callback):
+        """
+        To subscribe to a topic, just give the callback to call
+        Note that the callback must be a function whose first argument is a context
+        :param topic:
+        :param callback:
+        :return:
+        """
+        with self._lock:
+            self.subscribers.setdefault(topic, []).append(callback)
+
+    def publish(self, context, topic, data=None):
+        """
+        Publish on a topic
+        The data is not mandatory
+        :param context:
+        :param topic:
+        :param data:
+        :return:
+        """
+        with self._lock:
+            try:
+                subscribers = self.subscribers[topic]
+                if data:
+                    for callback in subscribers:
+                        callback(context, data)
+                else:
+                    for callback in subscribers:
+                        callback(context)
+            except KeyError:
+                pass
+
+    def test_only_reset_service(self):
+        """
+        Remove all subscribers from a given topic
+        TO REMOVE once sheerka ontology is fully implemented
+        :return:
+        """
+        self.subscribers.clear()
diff --git a/src/services/SheerkaPython.py b/src/services/SheerkaPython.py
index f791b6e..5358519 100644
--- a/src/services/SheerkaPython.py
+++ b/src/services/SheerkaPython.py
@@ -13,6 +13,7 @@ from core.error import ErrorConcepts, ErrorContext, ErrorObj, MethodAccessError
 from core.python_fragment import PythonFragment
 from parsers.tokenizer import Token, TokenKind
 from services.BaseService import BaseService
+from services.SheerkaConceptManager import ConceptRef
 
 TO_DISABLED = ["breakpoint", "callable", "compile", "delattr", "eval", "exec", "exit", "input", "locals", "open",
                "print", "quit", "setattr"]
@@ -98,12 +99,12 @@ class PythonEvalError(ErrorObj):
 
 
 @dataclass
-class EvaluationRef:
+class ObjectRef:
     root: str
     attr: str
 
     def __eq__(self, other):
-        if not isinstance(other, EvaluationRef):
+        if not isinstance(other, ObjectRef):
             return False
 
         return self.root == other.root and self.attr == other.attr
@@ -126,7 +127,12 @@ class EvaluationContext:
 
 class MultipleResults:
     def __init__(self, *args):
-        self.items = args
+        self.items = []
+        for item in args:
+            if isinstance(item, MultipleResults):
+                self.items.extend(item.items)
+            else:
+                self.items.append(item)
 
     def __iter__(self):
         return iter(self.items)
@@ -153,6 +159,10 @@ class MultipleResults:
     def concepts_only(self):
         return MultipleResults(*[item for item in self.items if isinstance(item, Concept)])
 
+    def unique(self):
+        seen = set()
+        return MultipleResults(*[x for x in self.items if x not in seen and not seen.add(x)])
+
 
 class SheerkaPython(BaseService):
     """
@@ -368,7 +378,18 @@ class SheerkaPython(BaseService):
         return result
 
     def resolve_object(self, context, attr_name, to_resolve, global_namespace):
-        if isinstance(to_resolve, EvaluationRef):
+        if isinstance(to_resolve, MultipleResults):
+            return MultipleResults(*(self.resolve_object(context, attr_name, item, global_namespace)
+                                     for item in to_resolve.items)).unique()
+
+        if isinstance(to_resolve, Concept):
+            to_resolve = context.sheerka.evaluate_concept(context, to_resolve)
+            return to_resolve
+
+        if isinstance(to_resolve, ConceptRef):
+            return self.new_concept(context, to_resolve)
+
+        if isinstance(to_resolve, ObjectRef):
             return getattr(global_namespace[to_resolve.root], to_resolve.attr)
 
         if isinstance(to_resolve, Token) and to_resolve.type == TokenKind.CONCEPT:
@@ -519,6 +540,16 @@ class SheerkaPython(BaseService):
 
     @staticmethod
     def new_concept(context, identifier):
+        """
+        Instantiate and evaluate a new concept, from its identifier
+        This method can return MultipleResult
+        :param context:
+        :type context:
+        :param identifier:
+        :type identifier:
+        :return:
+        :rtype:
+        """
         new_concept = context.sheerka.new(identifier)
 
         if isinstance(new_concept, list):
diff --git a/tests/caching/test_DictionaryCache.py b/tests/caching/test_DictionaryCache.py
index acb2363..0fde0fb 100644
--- a/tests/caching/test_DictionaryCache.py
+++ b/tests/caching/test_DictionaryCache.py
@@ -142,7 +142,7 @@ class TestDictionaryCache(BaseTest):
         assert cache.get("key") is NotFound
         assert cache._cache == {}
 
-    def test_auto_configure_retrieves_the_whole_remote_repository(self, sdp, context):
+    def test_auto_configure_retrieves_the_whole_remote_repository(self, context, sdp):
         cache = DictionaryCache(sdp=sdp).auto_configure("test")
         with sdp.get_transaction(context.event) as transaction:
             transaction.add("test", "key1", "value1")
@@ -153,7 +153,7 @@ class TestDictionaryCache(BaseTest):
 
         assert cache.copy() == {'key1': 'value1', 'key2': 'value2'}
 
-    def test_we_do_no_go_twice_in_repo_when_not_found(self, sdp, context):
+    def test_we_do_no_go_twice_in_repo_when_not_found(self, context, sdp):
         cache = DictionaryCache(sdp=sdp).auto_configure("test")
 
         assert cache.get("key") is NotFound
@@ -163,3 +163,61 @@ class TestDictionaryCache(BaseTest):
             transaction.add("test", "key", "value")
 
         assert cache.get("key") is NotFound  # the key was previously requested
+
+    def test_i_can_add_path(self):
+        cache = DictionaryCache()
+
+        cache.add_path(["a", "b", "c"], "c_value")
+        cache.add_path(["a", "b", "d", "e"], "e_value")
+
+        assert cache.copy() == {'a': {'b': {'c': {"#values#": ['c_value']},
+                                            'd': {'e': {"#values#": ['e_value']}}}}}
+        assert len(cache) == 2
+
+    def test_i_can_get_multiple_values_in_the_same_path(self):
+        cache = DictionaryCache()
+
+        cache.add_path(["a", "b", "c"], "value1")
+        cache.add_path(["a", "b", "c"], "value2")
+        cache.add_path(["a", "b", "c", "d"], "value3")
+
+        assert cache.copy() == {'a': {'b': {'c': {'d': {'#values#': ['value3']},
+                                                  '#values#': ["value1", "value2"]}}}}
+        assert len(cache) == 3
+
+    def test_i_can_remove_path(self):
+        cache = DictionaryCache()
+
+        cache.add_path(["a", "b", "c"], "value1")
+        cache.add_path(["a", "b", "c"], "value2")
+
+        cache.remove_path(["a", "b", "c"], "value1")
+        assert cache.copy() == {'a': {'b': {'c': {"#values#": ['value2']}}}}
+        assert len(cache) == 1
+
+        cache.remove_path(["a", "b", "c"], "value2")
+        assert cache.copy() == {}
+        assert len(cache) == 0
+
+    def test_i_can_remove_when_not_exist(self):
+        # remove an entry that does not exist does not cause error
+
+        cache = DictionaryCache()
+
+        cache.add_path(["a", "b", "c"], "value1")
+        cache.add_path(["a", "b", "c"], "value2")
+
+        cache.remove_path(["a", "b", "c"], "value3")
+        cache.remove_path(["a", "b"], "value1")
+
+        assert cache.copy() == {'a': {'b': {'c': {"#values#": ['value1', 'value2']}}}}
+        assert len(cache) == 2
+
+    def test_i_can_get_from_path(self):
+        cache = DictionaryCache()
+
+        cache.add_path(["a", "b", "c"], "value1")
+        cache.add_path(["a", "b", "c"], "value2")
+
+        assert cache.get_from_path(["a", "b"]) is NotFound
+        assert cache.get_from_path(["a", "b", "c"]) == ["value1", "value2"]
diff --git a/tests/caching/test_FastCache.py b/tests/caching/test_FastCache.py
index f55706c..b58bcd8 100644
--- a/tests/caching/test_FastCache.py
+++ b/tests/caching/test_FastCache.py
@@ -51,6 +51,15 @@ def test_not_found_is_returned_when_not_found():
     assert cache.get("foo") is NotFound
 
 
+def test_i_can_remove_an_item():
+    cache = FastCache()
+    cache.put("key1", "value1")
+    cache.put("to_keep1", "to_keep_value1")
+
+    cache.remove("key1")
+    assert cache.cache == {"to_keep1": "to_keep_value1"}
+
+
 def test_i_can_evict_by_key():
     cache = FastCache()
     cache.put("key1", "value1")
@@ -109,3 +118,33 @@ def test_i_can_copy():
     cache.put("key3", "value3")
 
     assert cache.copy() == {"key1": "value1", "key2": "value2", "key3": "value3"}
+
+
+def test_i_can_take_snapshots_and_revert():
+    # Test that I can create restoration points
+    # and come back later to them
+    cache = FastCache()
+    cache.put("key1", "value1")
+    cache.snapshot()
+    cache.put("key2", "value2")
+    cache.put("key3", "value3")
+    cache.snapshot()
+    cache.put("key4", "value4")
+    cache.put("key5", "value5")
+
+    assert cache.cache == {"key1": "value1",
+                           "key2": "value2",
+                           "key3": "value3",
+                           "key4": "value4",
+                           "key5": "value5"}
+
+    cache.revert_snapshot()
+    assert cache.cache == {"key1": "value1",
+                           "key2": "value2",
+                           "key3": "value3"}
+
+    cache.revert_snapshot()
+    assert cache.cache == {"key1": "value1"}
+
+    cache.revert_snapshot()  # no effect if nothing to revert
+    assert cache.cache == {"key1": "value1"}
diff --git a/tests/caching/test_ListCache.py b/tests/caching/test_ListCache.py
index 803fc47..44fd019 100644
--- a/tests/caching/test_ListCache.py
+++ b/tests/caching/test_ListCache.py
@@ -278,4 +278,261 @@ class TestListCache(BaseTest):
         cache = ListCache(default=lambda k: ["old_value", "other old value"] if k == "old_key" else ["other new"])
         cache.update("old_key", "old_value", "new_key", "new_value")
         assert cache.get("old_key") == ["other old value"]
-        assert cache.get("new_key") == ["other new", "new_value"]
\ No newline at end of file
+        assert cache.get("new_key") == ["other new", "new_value"]
+
+    def test_i_can_delete_from_list_cache(self):
+        cache = ListCache()
+        cache.put("key", "value")
+        cache.put("key", "value2")  # we can append to this list
+
+        cache.delete("key", "value2")
+
+        assert len(cache) == 1
+        assert cache.get("key") == ["value"]
+
+        cache.delete("key", "value")
+
+        assert len(cache) == 0
+        assert cache.get("key") is NotFound
+
+    def test_delete_an_entry_that_does_not_exist_has_no_effect(self):
+        cache = ListCache()
+        cache.put("key", "value")
+
+        cache.delete("key", "value2")
+
+        assert len(cache) == 1
+        assert cache.get("key") == ["value"]
+
+    def test_i_can_delete_when_alt_sdp_a_key_from_cache(self):
+        # There is a value in alt_cache_manager,
+        # No remaining value in current cache after deletion
+        # The key must be flagged as Removed
+        cache = ListCache(sdp=FakeSdp(get_value=lambda cache_name, key: NotFound)).auto_configure("cache_name")
+        cache.put("key", "value")
+
+        cache.delete("key", value=None, alt_sdp=FakeSdp(extend_exists=lambda cache_name, key: True))
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_cache(self):
+        # There is a value in alt_cache_manager,
+        # No remaining value in current cache after deletion
+        # The key must be flagged as Removed
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+        cache.put("key", "value")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_cache_and_then_put_back(self):
+        # There is a value in alt_cache_manager,
+        # No remaining value in current cache after deletion
+        # The key must be flagged as Removed
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+        cache.put("key", "value")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value", alt_sdp=alt_sdp)  # remove all values
+        cache.put("key", "value")
+
+        assert cache.copy() == {"key": ["value"]}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_cache_remaining_one_value(self):
+        # There is a value in alt_cache_manager,
+        # But this, there are remaining values in current cache after deletion
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+        cache.put("key", "value")
+        cache.put("key", "value2")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": ["value2"]}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_cache_remaining_values(self):
+        # There is a value in alt_cache_manager,
+        # But this, there are remaining values in current cache after deletion
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+        cache.put("key", "value")
+        cache.put("key", "value2")
+        cache.put("key", "value3")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": ['value2', 'value3']}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_key_from_remote_repository(self):
+        # There is a value in alt_cache_manager,
+        # No remaining value in current cache after deletion
+        # The key must be flagged as Removed
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: ["value1", "value2"])).auto_configure(
+            "cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value=None, alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_remote_repository(self):
+        # There is a value in alt_cache_manager,
+        # No remaining value in current cache after deletion
+        # The key must be flagged as Removed
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: ["value"])).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_key_from_remote_repository_and_then_put_back(self):
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: ["value1", "value2"])).auto_configure(
+            "cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["xxx"], extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value=None, alt_sdp=alt_sdp)  # remove all values
+        cache.put("key", "value")
+
+        assert cache.copy() == {"key": ["value"]}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_remote_repository_remaining_one_value(self):
+        # There is a value in alt_cache_manager,
+        # But this time, there are remaining values in current cache after deletion
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: ["value1", "value2"])).auto_configure(
+            "cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "xxx", extend_exists=lambda cache_name, key: True)
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": ["value2"]}
+        assert cache.to_remove == set()
+        assert cache.to_add == {"key"}
+
+    def test_i_can_delete_when_alt_sdp_a_key_from_alt_sdp(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # After value deletion, the key is empty
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["value1, value2"],
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.delete("key", value=None, alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_alt_sdp(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # After value deletion, the key is empty
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["value1"],
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": Removed}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_alt_sdp_and_then_put_back(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # After value deletion, the key is empty
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["value1"],
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        cache.put("key", "value")
+
+        assert cache.copy() == {"key": ["value"]}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_alt_sdp_one_value_remaining(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # After value deletion, one value remains in the cache
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["value1", "value2"],
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": ["value2"]}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_a_value_from_alt_sdp_multiple_values_remaining(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # After value deletion, one value remains in the cache
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: ["value1", "value2", "value3"],
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        assert cache.copy() == {"key": ["value2", "value3"]}
+        assert cache.to_add == {"key"}
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_an_already_removed_value_from_alt_sdp(self):
+        # alt_cache_manager is used because no value in cache or in remote repository
+        # But the alternate sdp returns Removed, which means that previous value was deleted
+        # It's like there is nothing to delete
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: Removed,
+                          extend_exists=lambda cache_name, key: False)
+
+        cache.delete("key", value="value1", alt_sdp=alt_sdp)
+        assert cache.copy() == {}
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
+    def test_deleting_an_entry_that_does_not_exist_is_not_an_error(self):
+        cache = ListCache()
+        cache.put("key", "value1")
+
+        cache.reset_events()
+        cache.delete("key3")
+        assert len(cache) == 1
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
+        cache.delete("key3", "value")
+        assert len(cache) == 1
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
+        cache.delete("key", "value2")
+        assert len(cache) == 1
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
+    def test_i_can_delete_when_alt_sdp_and_cache_is_cleared(self):
+        cache = ListCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
+        alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "value",
+                          extend_exists=lambda cache_name, key: True)
+
+        cache.clear()
+        cache.delete("key", value=None, alt_sdp=alt_sdp)
+        assert cache.copy() == {}
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
+        cache.delete("key", value="value", alt_sdp=alt_sdp)
+        assert cache.copy() == {}
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
diff --git a/tests/caching/test_ListIfNeededCache.py b/tests/caching/test_ListIfNeededCache.py
index 9593a0a..b46b2f6 100644
--- a/tests/caching/test_ListIfNeededCache.py
+++ b/tests/caching/test_ListIfNeededCache.py
@@ -610,6 +610,17 @@ class TestListIfNeededCache(BaseTest):
         assert cache.to_add == set()
         assert cache.to_remove == set()
 
+    def test_deleting_an_entry_that_does_not_exist_from_a_list_is_not_an_error(self):
+        cache = ListIfNeededCache()
+        cache.put("key", "value1")
+        cache.put("key", "value2")
+        cache.reset_events()
+
+        cache.delete("key", "value3")
+        assert len(cache) == 2
+        assert cache.to_add == set()
+        assert cache.to_remove == set()
+
     def test_i_can_delete_when_alt_sdp_and_cache_is_cleared(self):
         cache = ListIfNeededCache(sdp=FakeSdp(get_value=lambda entry, k: NotFound)).auto_configure("cache_name")
         alt_sdp = FakeSdp(get_alt_value=lambda cache_name, key: "value",
@@ -645,4 +656,4 @@ class TestListIfNeededCache(BaseTest):
 
         assert cache.copy() == {"key": "value"}
         assert cache.to_remove == set()
-        assert cache.to_add == {"key"}
\ No newline at end of file
+        assert cache.to_add == {"key"}
diff --git a/tests/conftest.py b/tests/conftest.py
index 9b2523a..894a5bf 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,8 +1,12 @@
+import inspect
+
 import pytest
 
 from helpers import GetNextId
 from server.authentication import User
 
+DEFAULT_ONTOLOGY_NAME = "current_test_"
+
 
 @pytest.fixture(scope="session")
 def sheerka():
@@ -75,12 +79,15 @@ class NewOntology:
     """
     from core.ExecutionContext import ExecutionContext
 
-    def __init__(self, context: ExecutionContext, name="current_test"):
+    def __init__(self, context: ExecutionContext, name=None):
         self.sheerka = context.sheerka
         self.context = context
         self.name = name
         self.ontology = None
 
+        if self.name is None:
+            self.name = inspect.stack()[1][3]
+
     def __enter__(self):
         self.ontology = self.sheerka.om.push_ontology(self.name)
         return self.ontology
diff --git a/tests/evaluators/test_DefConceptEvaluator.py b/tests/evaluators/test_DefConceptEvaluator.py
index 0ec1ce8..bb84a2d 100644
--- a/tests/evaluators/test_DefConceptEvaluator.py
+++ b/tests/evaluators/test_DefConceptEvaluator.py
@@ -92,3 +92,16 @@ class TestDefConceptEvaluator(BaseTest):
             new_concept = res.new[0].value
             assert context.sheerka.isinstance(new_concept, BuiltinConcepts.NEW_CONCEPT)
             assert new_concept.body.variables == expected
+            assert new_concept.body.parameters == set(item[0] for item in expected)
+
+    def test_i_can_define_variables_that_are_not_parameters(self, context, evaluator):
+        with NewOntology(context, "test_i_can_define_variables_that_are_not_parameters"):
+            ret_val_input = get_ret_val_from(context, "def concept color def_var color_name")
+            res = evaluator.eval(context, None, ret_val_input)
+
+            assert len(res.new) == 1
+            assert res.new[0].status
+            new_concept = res.new[0].value
+            assert context.sheerka.isinstance(new_concept, BuiltinConcepts.NEW_CONCEPT)
+            assert new_concept.body.variables == [("color_name", NotInit)]
+            assert new_concept.body.parameters == set()
diff --git a/tests/evaluators/test_FilterSuccessful.py b/tests/evaluators/test_FilterSuccessful.py
new file mode 100644
index 0000000..7b402d9
--- /dev/null
+++ b/tests/evaluators/test_FilterSuccessful.py
@@ -0,0 +1,51 @@
+import pytest
+
+from base import BaseTest
+from evaluators.FilterSuccessful import FilterSuccessful
+from helpers import _rv, _rvf
+
+
+class TestFilterSuccessful(BaseTest):
+    @pytest.fixture()
+    def evaluator(self, sheerka):
+        return sheerka.evaluators[FilterSuccessful.NAME]
+
+    def test_i_can_match_and_eval(self, context, evaluator):
+        true1 = _rv("some_value1")
+        true2 = _rv("some_value2")
+        false1 = _rvf("some_value1")
+        false2 = _rvf("some_value2")
+
+        return_values = [true1]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        return_values = [true1, true2]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        return_values = [false1]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        return_values = [false1, false2]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        return_values = [true1, false1]
+        m = evaluator.matches(context, return_values)
+        assert m.status is True
+        assert m.obj == {'to_keep': [true1], 'to_drop': [false1]}
+
+        r = evaluator.eval(context, m.obj, return_values)
+        assert r.new == [true1]
+        assert r.eaten == [false1]
+
+        return_values = [true1, true2, false1, false2]
+        m = evaluator.matches(context, return_values)
+        assert m.status is True
+        assert m.obj == {'to_keep': [true1, true2], 'to_drop': [false1, false2]}
+
+        r = evaluator.eval(context, m.obj, return_values)
+        assert r.new == [true1, true2]
+        assert r.eaten == [false1, false2]
diff --git a/tests/evaluators/test_RecognizeSimpleConcept.py b/tests/evaluators/test_RecognizeSimpleConcept.py
new file mode 100644
index 0000000..51d9c6c
--- /dev/null
+++ b/tests/evaluators/test_RecognizeSimpleConcept.py
@@ -0,0 +1,48 @@
+import pytest
+
+from base import BaseParserTest
+from conftest import NewOntology
+from core.BuiltinConcepts import BuiltinConcepts
+from evaluators.RecognizeSimpleConcept import RecognizeSimpleConcept
+from evaluators.base_evaluator import NotForMe
+from helpers import _rv, _rvf, get_concepts
+from parsers.ParserInput import ParserInput
+
+
+class TestRecognizeSimpleConcept(BaseParserTest):
+    @pytest.fixture()
+    def evaluator(self, sheerka):
+        return sheerka.evaluators[RecognizeSimpleConcept.NAME]
+
+    def test_i_can_match(self, sheerka, context, evaluator):
+        ret_val = _rv(sheerka.newn(BuiltinConcepts.PARSER_INPUT, pi=ParserInput("some text")))
+        assert evaluator.matches(context, ret_val).status is True
+
+        ret_val = _rv(sheerka.newn(BuiltinConcepts.UNKNOWN_CONCEPT))  # it responds to USER_INPUT only
+        assert evaluator.matches(context, ret_val).status is False
+
+        ret_val = _rvf(sheerka.newn(BuiltinConcepts.PARSER_INPUT, pi=ParserInput("some text")))  # status is false
+        assert evaluator.matches(context, ret_val).status is False
+
+    def test_i_can_recognize_a_concept(self, context, evaluator):
+        with NewOntology(context, "test_i_can_recognize_a_def_concept"):
+            concept, = get_concepts(context, "I am a new concept", use_sheerka=True)
+
+            ret_val_input = self.get_parser_input(context, "I am a new concept")
+            res = evaluator.eval(context, None, ret_val_input)
+
+            assert len(res.new) == 1
+            assert res.new[0].status
+            assert context.sheerka.isinstance(res.new[0].value, concept)
+
+            assert res.eaten == [ret_val_input]
+
+    def test_i_do_not_eat_when_not_for_me(self, context, evaluator):
+        with NewOntology(context, "test_i_can_recognize_a_def_concept"):
+            ret_val_input = self.get_parser_input(context, "unknown concept")
+            res = evaluator.eval(context, None, ret_val_input)
+
+            assert len(res.new) == 1
+            assert not res.new[0].status
+            assert isinstance(res.new[0].value, NotForMe)
+            assert len(res.eaten) == 0
diff --git a/tests/evaluators/test_ResolvePythonVsSimpleConcept.py b/tests/evaluators/test_ResolvePythonVsSimpleConcept.py
new file mode 100644
index 0000000..b7a9f49
--- /dev/null
+++ b/tests/evaluators/test_ResolvePythonVsSimpleConcept.py
@@ -0,0 +1,57 @@
+import pytest
+
+from base import BaseTest
+from evaluators.PythonParser import PythonParser
+from evaluators.RecognizeDefConcept import RecognizeDefConcept
+from evaluators.RecognizeSimpleConcept import RecognizeSimpleConcept
+from evaluators.ResolvePythonVsSimpleConcept import ResolvePythonVsSimpleConcept
+from helpers import _rv, _rvf
+
+
+class TestResolvePythonVsSimpleConcept(BaseTest):
+    @pytest.fixture()
+    def evaluator(self, sheerka):
+        return sheerka.evaluators[ResolvePythonVsSimpleConcept.NAME]
+
+    def test_i_can_match_and_eval(self, context, evaluator):
+        python = _rv("some_value", who=PythonParser.NAME)
+        concept = _rv("some_value", who=RecognizeSimpleConcept.NAME)
+        other = _rv("some_value", who=RecognizeDefConcept.NAME)
+        python_nok = _rvf("some_value", who=PythonParser.NAME)
+        concept_nok = _rvf("some_value", who=RecognizeSimpleConcept.NAME)
+        other_nok = _rvf("some_value", who=RecognizeDefConcept.NAME)
+
+        # at least the two
+        return_values = [python, concept]
+        m = evaluator.matches(context, return_values)
+        assert m.status is True
+        assert m.obj == {'to_keep': concept, 'to_drop': python, 'others': []}
+
+        r = evaluator.eval(context, m.obj, return_values)
+        assert r.new == [concept]
+        assert r.eaten == [python]
+
+        # the two and other successful
+        return_values = [python, concept, other, other_nok]
+        m = evaluator.matches(context, return_values)
+        assert m.status is True
+        assert m.obj == {'to_keep': concept, 'to_drop': python, 'others': [other, other_nok]}
+
+        r = evaluator.eval(context, m.obj, return_values)
+        assert r.new == [concept, other, other_nok]
+        assert r.eaten == [python]
+
+        # python is not ok
+        return_values = [python_nok, concept]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        # concept is not ok
+        return_values = [python, concept_nok]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
+
+        # neither is not
+        return_values = [python_nok, concept_nok]
+        m = evaluator.matches(context, return_values)
+        assert m.status is False
diff --git a/tests/helpers.py b/tests/helpers.py
index cedf84c..053b692 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -1,7 +1,11 @@
 from common.global_symbols import NotInit
+from common.utils import unstr_concept
 from core.ExecutionContext import ExecutionContext
 from core.ReturnValue import ReturnValue
 from core.concept import Concept, ConceptDefaultProps, ConceptMetadata, DefinitionType
+from parsers.ParserInput import ParserInput
+from parsers.state_machine import MetadataToken, UnrecognizedToken
+from parsers.tokenizer import Tokenizer
 from services.SheerkaConceptManager import ConceptManager
 
 ATTR_MAP = {
@@ -122,7 +126,34 @@ def get_evaluated_concept(blueprint: Concept | ConceptMetadata, **kwargs):
     :return:
     :rtype:
     """
+
+    def _isfloat(num):
+        try:
+            float(num)
+            return True
+        except ValueError:
+            return False
+
     res = Concept(blueprint.get_metadata())
+
+    for attr in ATTR_MAP:
+        source_code = getattr(res.get_metadata(), attr)
+        if source_code == "" or source_code is None:
+            value = NotInit
+        elif source_code[0] in ("'", '"'):
+            value = source_code[1:-1]
+        elif source_code in ("True", "False"):
+            value = source_code == "True"
+        elif source_code.isdecimal():
+            value = int(source_code)
+        elif _isfloat(source_code):
+            value = float(source_code)
+        else:
+            raise Exception(f"Cannot manage {attr=}, {source_code=}")
+
+        setattr(res, ATTR_MAP[attr], value)
+
+    # force values
     for k, v in kwargs.items():
         res.set_value(ATTR_MAP.get(k, k), v)
 
@@ -347,6 +378,13 @@ def get_concepts(context: ExecutionContext, *concepts, **kwargs) -> list[Concept
     return res
 
 
+def get_evaluated_concepts(context, *concepts, use_sheerka=False) -> list[Concept]:
+    if use_sheerka:
+        return [context.sheerka.evaluate_concept(context, Concept(c.get_metadata())) for c in concepts]
+    else:
+        return [get_evaluated_concept(concept) for concept in concepts]
+
+
 def define_new_concept(context: ExecutionContext, c: str | Concept | ConceptMetadata) -> Concept:
     sheerka = context.sheerka
     if isinstance(c, str):
@@ -381,6 +419,43 @@ def get_file_content(file_name):
         return f.read()
 
 
+def get_parser_input(text):
+    pi = ParserInput(text)
+    assert pi.init()
+
+    return pi
+
+
+def get_from(*args, **kwargs):
+    """
+    Convert the input to fix the positions
+    :param args:
+    :type args:
+    :return:
+    :rtype:
+    """
+    cache = {}  # I keep the name in cache to avoid having to remind it everytime
+    pos = 0
+    res = []
+    for item in args:
+        start = pos
+        if isinstance(item, MetadataToken):
+            if item.metadata.name:
+                cache[item.metadata.id] = item.metadata.name
+
+            tokens = list(Tokenizer(cache[item.metadata.id], yield_eof=False))
+            pos += len(tokens)
+            resolution_method = kwargs.get("resolution_method", item.resolution_method)
+            parser = kwargs.get("parser", item.parser)
+            res.append(MetadataToken(item.metadata, start, pos - 1, resolution_method, parser))
+        elif isinstance(item, UnrecognizedToken):
+            tokens = list(Tokenizer(item.buffer, yield_eof=False))
+            pos += len(tokens)
+            res.append(UnrecognizedToken(item.buffer, start, pos - 1))
+
+    return res
+
+
 def _rv(value, who="Test"):
     return ReturnValue(who=who, status=True, value=value)
 
@@ -400,3 +475,37 @@ def _rvf(value, who="Test"):
     :rtype:
     """
     return ReturnValue(who=who, status=False, value=value)
+
+
+def _ut(buffer, start=0, end=-1):
+    """
+    helper to UnrecognizedToken
+    :param buffer:
+    :type buffer:
+    :param start:
+    :type start:
+    :param end:
+    :type end:
+    :return:
+    :rtype:
+    """
+    return UnrecognizedToken(buffer, start, end)
+
+
+def _mt(concept_id, start=0, end=-1, resolution_method="id", parser="simple"):
+    """
+    helper to MetadataToken
+    :param concept_id:
+    :type concept_id:
+    :param start:
+    :type start:
+    :param end:
+    :type end:
+    :return:
+    :rtype:
+    """
+    name, _id = unstr_concept(concept_id)
+    if _id is None:
+        return MetadataToken(get_metadata(id=concept_id), start, end, resolution_method, parser)
+    else:
+        return MetadataToken(get_metadata(id=_id, name=name), start, end, resolution_method, parser)
diff --git a/tests/non_reg/test_non_reg1.py b/tests/non_reg/test_non_reg1.py
index 643b600..a5d63c4 100644
--- a/tests/non_reg/test_non_reg1.py
+++ b/tests/non_reg/test_non_reg1.py
@@ -1,4 +1,6 @@
 from base import BaseTest
+from conftest import NewOntology
+from core.BuiltinConcepts import BuiltinConcepts
 
 
 def get_ret_val(res):
@@ -17,9 +19,9 @@ class TestNonReg1(BaseTest):
 
     def test_i_cannot_evaluate_variable_that_is_not_defined(self, sheerka, user):
         res = sheerka.evaluate_user_input("a", user)
-        ret_val = get_ret_val(res)
 
-        assert ret_val.status is False
+        assert len(res) == 2
+        assert all([not ret_val.status for ret_val in res])
 
     def test_i_can_remember_variables(self, sheerka, user):
         sheerka.evaluate_user_input("a = 10", user)
@@ -28,3 +30,51 @@ class TestNonReg1(BaseTest):
         ret_val = get_ret_val(res)
 
         assert ret_val.value == 10
+
+    def test_i_can_define_a_new_concept(self, context, sheerka, user):
+        with NewOntology(context, "test_i_can_define_a_new_concept"):
+            res = sheerka.evaluate_user_input("def concept one as 1", user)
+
+            ret_val = get_ret_val(res)
+            assert ret_val.status
+            assert sheerka.isinstance(ret_val.value, BuiltinConcepts.NEW_CONCEPT)
+
+    def test_i_can_define_a_new_concept_and_use_it(self, context, sheerka, user):
+        with NewOntology(context, "test_i_can_define_a_new_concept_and_use_it"):
+            sheerka.evaluate_user_input("def concept one as 1", user)
+
+            res = sheerka.evaluate_user_input("one", user)
+            ret_val = get_ret_val(res)
+            assert ret_val.status
+            assert sheerka.isinstance(ret_val.value, "one")
+            assert not ret_val.value.get_runtime_info().is_evaluated
+
+    def test_i_can_get_i_concept_using_c_name_form(self, context, sheerka, user):
+        with NewOntology(context):
+            sheerka.evaluate_user_input("def concept one as 1", user)
+
+            res = sheerka.evaluate_user_input("c:one:", user)
+            ret_val = get_ret_val(res)
+            assert ret_val.status
+            assert sheerka.isinstance(ret_val.value, "one")
+            assert not ret_val.value.get_runtime_info().is_evaluated
+
+    def test_i_can_get_i_concept_using_c_id_form(self, context, sheerka, user):
+        with NewOntology(context):
+            sheerka.evaluate_user_input("def concept one as 1", user)
+
+            res = sheerka.evaluate_user_input("c:#1001:", user)
+            ret_val = get_ret_val(res)
+            assert ret_val.status
+            assert sheerka.isinstance(ret_val.value, "one")
+            assert not ret_val.value.get_runtime_info().is_evaluated
+
+    def test_i_can_recognize_concepts_with_long_name(self, context, sheerka, user):
+        with NewOntology(context):
+            sheerka.evaluate_user_input("def concept i am a concept", user)
+
+            res = sheerka.evaluate_user_input("i am a concept", user)
+            ret_val = get_ret_val(res)
+            assert ret_val.status
+            assert sheerka.isinstance(ret_val.value, "i am a concept")
+            assert not ret_val.value.get_runtime_info().is_evaluated
diff --git a/tests/parsers/test_DefConceptParser.py b/tests/parsers/test_ConceptDefinitionParser.py
similarity index 98%
rename from tests/parsers/test_DefConceptParser.py
rename to tests/parsers/test_ConceptDefinitionParser.py
index 3758847..463d5d0 100644
--- a/tests/parsers/test_DefConceptParser.py
+++ b/tests/parsers/test_ConceptDefinitionParser.py
@@ -2,22 +2,15 @@ import pytest
 
 from common.global_symbols import NotInit
 from core.concept import DefinitionType
+from helpers import get_parser_input
 from parsers.ConceptDefinitionParser import ConceptDefinition, ConceptDefinitionParser
-from parsers.ParserInput import ParserInput
 from parsers.parser_utils import ParsingError, UnexpectedEof, UnexpectedToken
 from parsers.tokenizer import Keywords, Token, TokenKind
 
 
-def get_parser_input(text):
-    pi = ParserInput(text)
-    assert pi.init()
-
-    return pi
-
-
-class TestRecognizeDefConcept:
+class TestConceptDefinitionParser:
     @pytest.fixture()
-    def parser(self, sheerka):
+    def parser(self):
         return ConceptDefinitionParser()
 
     @pytest.mark.parametrize("text", [
diff --git a/tests/parsers/test_SimpleConceptsParser.py b/tests/parsers/test_SimpleConceptsParser.py
new file mode 100644
index 0000000..1a6d82b
--- /dev/null
+++ b/tests/parsers/test_SimpleConceptsParser.py
@@ -0,0 +1,142 @@
+import pytest
+
+from base import BaseTest
+from conftest import NewOntology
+from evaluators.base_evaluator import MultipleChoices
+from helpers import _mt, _ut, get_concepts, get_from, get_metadata, get_parser_input
+from parsers.SimpleParserParser import SimpleConceptsParser
+
+
+class TestSimpleConceptsParser(BaseTest):
+
+    @pytest.fixture()
+    def parser(self):
+        return SimpleConceptsParser()
+
+    @pytest.mark.parametrize("text, expected", [
+        ("I am a new concept", [_mt("1003", 0, 8)]),
+        ("xxx yyy I am a new concept", [_ut("xxx yyy ", 0, 3), _mt("1003", 4, 12)]),
+        ("I am a new concept xxx yyy", [_mt("1003", 0, 8), _ut(" xxx yyy", 9, 12)]),
+        ("xxx I am a new concept yyy", [_ut("xxx ", 0, 1), _mt("1003", 2, 10), _ut(" yyy", 11, 12)]),
+        ("c:#1003:", [_mt("1003", 0, 0)]),
+        ("xxx c:#1003: yyy", [_ut("xxx ", 0, 1), _mt("1003", 2, 2), _ut(" yyy", 3, 4)]),
+        ("xxx c:I am: yyy", [_ut("xxx ", 0, 1), _mt("1002", 2, 2), _ut(" yyy", 3, 4)]),
+        (" I am a new concept", [_ut(" ", 0, 0), _mt("1003", 1, 9)])
+    ])
+    def test_i_can_recognize_a_concept(self, context, parser, text, expected):
+        with NewOntology(context, "test_i_can_recognize_a_concept"):
+            get_concepts(context, "I", "I am", "I am a new concept", use_sheerka=True)
+
+            pi = get_parser_input(text)
+            res = parser.parse(context, pi)
+
+            assert res == MultipleChoices([expected])
+            assert not parser.error_sink
+
+    @pytest.mark.parametrize("text, expected", [
+        ("foo", [_mt("1001", 0, 0)]),
+        ("I am a new concept", [_mt("1001", 0, 8)])
+    ])
+    def test_i_can_recognize_a_concept_by_its_name_and_its_definition(self, context, parser, text, expected):
+        with NewOntology(context, "test_i_can_recognize_a_concept_by_its_name_and_its_definition"):
+            get_concepts(context, get_metadata(name="foo", definition="I am a new concept"), use_sheerka=True)
+
+            pi = get_parser_input(text)
+            res = parser.parse(context, pi)
+
+            assert res == MultipleChoices([expected])
+            assert not parser.error_sink
+
+    @pytest.mark.parametrize("text, expected", [
+        ("long concept name", [_mt("1001", 0, 4)]),
+        ("I am a new concept", [_mt("1001", 0, 8)])
+    ])
+    def test_i_can_recognize_a_concept_by_its_name_when_long_name(self, context, parser, text, expected):
+        with NewOntology(context, "test_i_can_recognize_a_concept_by_its_name_when_long_name"):
+            get_concepts(context, get_metadata(name="long concept name", definition="I am a new concept"),
+                         use_sheerka=True)
+
+            pi = get_parser_input(text)
+            res = parser.parse(context, pi)
+
+            assert res == MultipleChoices([expected])
+            assert not parser.error_sink
+
+    def test_i_can_parse_a_sequence_of_concept(self, context, parser):
+        with NewOntology(context, "test_i_can_parse_a_sequence_of_concept"):
+            get_concepts(context, "foo bar", "baz", "qux", use_sheerka=True)
+
+            pi = get_parser_input("foo bar baz foo, qux")
+            res = parser.parse(context, pi)
+
+            expected = [_mt("1001", 0, 2),
+                        _ut(" ", 3, 3),
+                        _mt("1002", 4, 4),
+                        _ut(" foo, ", 5, 8),
+                        _mt("1003", 9, 9)]
+
+            assert res == MultipleChoices([expected])
+            assert not parser.error_sink
+
+    def test_i_can_detect_multiple_choices(self, context, parser):
+        with NewOntology(context, "test_i_can_detect_multiple_choices"):
+            get_concepts(context, "foo bar", "bar baz", use_sheerka=True)
+
+            pi = get_parser_input("foo bar baz")
+            res = parser.parse(context, pi)
+
+            expected1 = [_mt("1001", 0, 2), _ut(" baz", 3, 4)]
+            expected2 = [_ut("foo ", 0, 1), _mt("1002", 2, 4)]
+
+            assert res == MultipleChoices([expected1, expected2])
+            assert not parser.error_sink
+
+    def test_i_can_detect_multiple_choices_2(self, context, parser):
+        with NewOntology(context, "test_i_can_detect_multiple_choices_2"):
+            get_concepts(context, "one two", "one", "two", use_sheerka=True)
+
+            pi = get_parser_input("one two")
+            res = parser.parse(context, pi)
+
+            expected1 = [_mt("1001", 0, 2)]
+            expected2 = [_mt("1002", 0, 0), _ut(" ", 1, 1), _mt("1003", 2, 2)]
+
+            assert res == MultipleChoices([expected1, expected2])
+            assert not parser.error_sink
+
+    def test_i_can_detect_multiple_choices_3(self, context, parser):
+        with NewOntology(context, "test_i_can_detect_multiple_choices_2"):
+            get_concepts(context, "one two", "one", "two", use_sheerka=True)
+
+            pi = get_parser_input("one two xxx one two")
+            res = parser.parse(context, pi)
+
+            e1 = get_from(_mt("c:one two#1001:"), _ut(" xxx "), _mt("c:#1001:"))
+            e2 = get_from(_mt("c:one#1002:"), _ut(" "), _mt("c:two#1003:"), _ut(" xxx "), _mt("c:one two#1001:"))
+            e3 = get_from(_mt("c:one two#1001:"), _ut(" xxx "), _mt("c:one#1002:"), _ut(" "), _mt("c:two#1003:"))
+            e4 = get_from(_mt("c:one#1002:"), _ut(" "), _mt("c:two#1003:"), _ut(" xxx "), _mt("c:#1002:"), _ut(" "),
+                          _mt("c:#1003:"))
+
+            assert res == MultipleChoices([e1, e2, e3, e4])
+            assert not parser.error_sink
+
+    def test_nothing_is_return_is_no_concept_is_recognized(self, context, parser):
+        pi = get_parser_input("one two three")
+        res = parser.parse(context, pi)
+
+        assert res == MultipleChoices([])
+
+    def test_i_can_manage_attribute_reference(self, context, parser):
+        with NewOntology(context, "test_i_can_detect_multiple_choices_2"):
+            get_concepts(context, "foo", "i am a concept", use_sheerka=True)
+
+            pi = get_parser_input("foo.attribute")
+            res = parser.parse(context, pi)
+            expected = [_mt("1001", 0, 0), _ut(".attribute", 1, 2)]
+            assert res == MultipleChoices([expected])
+
+            pi = get_parser_input("i am a concept.attribute")
+            res = parser.parse(context, pi)
+            expected = [_mt("1002", 0, 6), _ut(".attribute", 7, 8)]
+            assert res == MultipleChoices([expected])
+
diff --git a/tests/parsers/test_state_machine.py b/tests/parsers/test_state_machine.py
new file mode 100644
index 0000000..c8b36ad
--- /dev/null
+++ b/tests/parsers/test_state_machine.py
@@ -0,0 +1,82 @@
+from dataclasses import dataclass
+
+from parsers.state_machine import End, Start, State, StateMachine, StateResult
+
+
+@dataclass
+class DummyExecutionContext:
+    count: int
+
+    def to_debug(self):
+        return {"count": self.count}
+
+
+class GenericTestState(State):
+    def __init__(self, name, next_state, fork=None):
+        super().__init__(name=name, next_states=[next_state])
+        self.next_state = next_state
+        self.fork = fork
+
+    def run(self, state_context) -> StateResult:
+        return StateResult(self.next_state, self.fork)
+
+    def __repr__(self):
+        return f"(GenericTestState {self.name} -> {self.next_state}, forks={len(self.fork) if self.fork else 0})"
+
+
+def test_i_can_execute_a_workflow():
+    wkf_as_list = [Start("start", ["a"]),
+                   GenericTestState("a", "b"),
+                   GenericTestState("b", "c"),
+                   GenericTestState("c", "end"),
+                   End("end", None)]
+
+    wkf = {state.name: state for state in wkf_as_list}
+
+    state_machine = StateMachine({"#wkf": wkf})
+    state_machine.run("#wkf", "start", DummyExecutionContext(0))
+
+    assert len(state_machine.paths) == 1
+    assert state_machine.paths[0].get_audit_trail() == ["#wkf:start", "#wkf:a", "#wkf:b", "#wkf:c", "#wkf:end"]
+
+
+def test_i_can_change_workflow():
+    wkf1_as_list = [Start("start", ["a"]),
+                    GenericTestState("a", "#wkf2")]
+
+    wkf2_as_list = [Start("start", ["c"]),
+                    GenericTestState("c", "end"),
+                    End("end", None)]
+
+    wkfs = {
+        "#wkf1": {state.name: state for state in wkf1_as_list},
+        "#wkf2": {state.name: state for state in wkf2_as_list}
+    }
+
+    state_machine = StateMachine(wkfs)
+    state_machine.run("#wkf1", "start", DummyExecutionContext(0))
+
+    assert len(state_machine.paths) == 1
+    assert state_machine.paths[0].get_audit_trail() == ["#wkf1:start", "#wkf1:a", "#wkf2:start", "#wkf2:c", "#wkf2:end"]
+
+
+def test_i_can_fork_path():
+    wkf_as_list = [Start("start", ["a"]),
+                   GenericTestState("a", "end", [("b", DummyExecutionContext(i)) for i in range(3)]),
+                   GenericTestState("b", "end"),
+                   End("end", None)]
+
+    wkf = {state.name: state for state in wkf_as_list}
+
+    state_machine = StateMachine({"#wkf": wkf})
+    state_machine.run("#wkf", "start", DummyExecutionContext(0))
+
+    assert len(state_machine.paths) == 4
+    assert state_machine.paths[0].get_audit_trail() == ["#wkf:start", "#wkf:a", "#wkf:end"]
+    assert state_machine.paths[0].history[1].forks == [1, 2, 3]
+    assert state_machine.paths[1].get_audit_trail() == ["#wkf:start", "#wkf:a", "#wkf:b", "#wkf:end"]
+    assert state_machine.paths[1].history[0].parents == [0]
+    assert state_machine.paths[2].get_audit_trail() == ["#wkf:start", "#wkf:a", "#wkf:b", "#wkf:end"]
+    assert state_machine.paths[2].history[0].parents == [0]
+    assert state_machine.paths[3].get_audit_trail() == ["#wkf:start", "#wkf:a", "#wkf:b", "#wkf:end"]
+    assert state_machine.paths[3].history[0].parents == [0]
diff --git a/tests/services/test_ConceptEvaluator.py b/tests/services/test_ConceptEvaluator.py
index 093cbfd..c63b6df 100644
--- a/tests/services/test_ConceptEvaluator.py
+++ b/tests/services/test_ConceptEvaluator.py
@@ -5,11 +5,10 @@ from common.global_symbols import NotInit
 from conftest import NewOntology
 from core.BuiltinConcepts import BuiltinConcepts
 from core.concept import ConceptDefaultProps
-from core.error import ErrorContext
 from core.python_fragment import PythonFragment
 from helpers import define_new_concept, get_concept, get_concepts, get_metadata
-from services.SheerkaConceptEvaluator import ConceptEvaluator
-from services.SheerkaPython import EvaluationRef
+from services.SheerkaConceptEvaluator import ConceptEvaluator, InfiniteRecursion, TooManyErrors
+from services.SheerkaPython import ObjectRef
 
 
 class TestConceptManager(BaseTest):
@@ -77,8 +76,8 @@ class TestConceptManager(BaseTest):
         compiled = service._build_attributes(context, metadata)
         pf = getattr(compiled, ConceptDefaultProps.BODY)
         assert isinstance(pf, PythonFragment)
-        assert pf.namespace == {"a": EvaluationRef("self", "a"),
-                                "b": EvaluationRef("self", "b")}
+        assert pf.namespace == {"a": ObjectRef("self", "a"),
+                                "b": ObjectRef("self", "b")}
 
     def test_i_can_manage_parsing_errors(self, context, service):
         metadata = get_metadata(
@@ -98,7 +97,7 @@ class TestConceptManager(BaseTest):
         assert pf.source_code == "NotInit"
 
         error = getattr(compiled, ConceptDefaultProps.BODY)
-        assert isinstance(error, ErrorContext)
+        assert isinstance(error, TooManyErrors)
 
     def test_i_can_eval_concept_attributes(self, context, service):
         with NewOntology(context, "test_i_can_eval_concept_attributes"):
@@ -225,6 +224,9 @@ class TestConceptManager(BaseTest):
             assert context.sheerka.objvalue(qux) == 1
 
     def test_concept_variables_precede_global_concepts(self, context, service):
+        # In this test, there is a variable named "foo"
+        # Its value is the concept 'bar'
+        # So when the body is evaluated, we expected Concept(bar), not Concept(foo)
         with NewOntology(context, "test_concept_variables_precede_global_concepts"):
             foo, bar, baz = get_concepts(context,
                                          get_concept("foo"),
@@ -237,6 +239,20 @@ class TestConceptManager(BaseTest):
             assert context.sheerka.isinstance(res, baz)
             assert context.sheerka.isinstance(res.body, bar)
 
+    def test_concept_variables_precede_global_concept_during_computation(self, context, service):
+        # In this test, there is a variable named "foo" and a concept also named "foo"
+        # When evaluated, foo + 1 must use the variable 'foo', not the Concept("foo")
+        with NewOntology(context, "test_concept_variables_precede_global_concepts"):
+            foo, bar = get_concepts(context,
+                                    get_concept("foo", body="2"),
+                                    get_concept("bar", body="foo + 1", variables=(("foo", "1"),)),
+                                    use_sheerka=True)
+
+            res = service.evaluate_concept(context, bar)
+
+            assert context.sheerka.isinstance(res, bar)
+            assert context.sheerka.objvalue(res) == 2
+
     def test_i_can_evaluate_concept_when_variables_reference_others_concepts_with_body(self, context, service):
         with NewOntology(context, "test_i_can_evaluate_concept_when_variables_reference_others_concepts_with_body"):
             foo, bar, baz = get_concepts(context,
@@ -463,6 +479,7 @@ class TestConceptManager(BaseTest):
             res = service.evaluate_concept(context, foo)
             assert context.sheerka.isinstance(res, BuiltinConcepts.EVALUATION_ERROR)
             assert context.sheerka.isinstance(res.concept, foo)
+            assert isinstance(res.reason, InfiniteRecursion)
             assert res.reason.ids == [foo.id, bar.id, baz.id]
 
     def test_i_can_detect_sub_infinite_loop(self, context, service):
@@ -476,6 +493,7 @@ class TestConceptManager(BaseTest):
             res = service.evaluate_concept(context, foo)
             assert context.sheerka.isinstance(res, BuiltinConcepts.EVALUATION_ERROR)
             assert context.sheerka.isinstance(res.concept, bar)
+            assert isinstance(res.reason, InfiniteRecursion)
             assert res.reason.ids == [bar.id, baz.id]
 
     def test_i_can_detect_auto_infinite_loop(self, context, service):
@@ -487,10 +505,11 @@ class TestConceptManager(BaseTest):
             res = service.evaluate_concept(context, foo)
             assert context.sheerka.isinstance(res, BuiltinConcepts.EVALUATION_ERROR)
             assert context.sheerka.isinstance(res.concept, foo)
+            assert isinstance(res.reason, InfiniteRecursion)
             assert res.reason.ids == [foo.id]
 
     def test_i_can_select_the_valid_result_when_multiple_choice_invalid_concept(self, context, service):
-        with NewOntology(context, "test_i_can_select_the_valid_result_when_multiple_choice"):
+        with NewOntology(context, "test_i_can_select_the_valid_result_when_multiple_choice_invalid_concept"):
             foo, two_ok, two_nok = get_concepts(context,
                                                 get_concept("foo", body="two"),
                                                 get_concept("two", body="1 +"),  # has to come before the other 'two'
@@ -502,7 +521,7 @@ class TestConceptManager(BaseTest):
             assert context.sheerka.objvalue(foo) == 2
 
     def test_i_can_select_the_valid_result_when_multiple_choice_evaluation_error(self, context, service):
-        with NewOntology(context, "test_i_can_select_the_valid_result_when_multiple_choice"):
+        with NewOntology(context, "test_i_can_select_the_valid_result_when_multiple_choice_evaluation_error"):
             foo, two_ok, two_nok = get_concepts(context,
                                                 get_concept("foo", body="two"),
                                                 get_concept("two", body="1 / 0"),  # has to come before the other 'two'
@@ -529,8 +548,35 @@ class TestConceptManager(BaseTest):
         with NewOntology(context, "test_i_do_not_use_ret_in_case_of_error"):
             foo, baz = get_concepts(context,
                                     get_concept("foo"),
-                                    get_concept("baz", body="foo", ret="bar"),
+                                    get_concept("baz", body="foo", ret="bar"),  # Concept("bar") is not defined
                                     use_sheerka=True)
 
             res = service.evaluate_concept(context, baz)
             assert context.sheerka.isinstance(res, BuiltinConcepts.EVALUATION_ERROR)
+
+    @pytest.mark.skip("Cannot remove concept")
+    def test_i_do_not_use_ret_in_case_of_error_when_concept_was_removed(self, context, service):
+        # Make sure that ret is not returned in case of UNKNOWN_CONCEPT error message
+        foo, bar, baz = get_concepts(context,
+                                     get_concept("foo"),
+                                     get_concept("bar"),
+                                     get_concept("baz", body="foo", ret="bar"),  # Concept("bar") is not defined
+                                     use_sheerka=True)
+        service.evaluate_concept(context, baz)  # creates the compiled for Concept("baz")
+        context.sheerka.remove_concept(bar)  # Concept("bar") no longer exists, but compiled for "baz" remains the same
+
+        res = service.evaluate_concept(context, baz)
+        assert context.sheerka.isinstance(res, BuiltinConcepts.EVALUATION_ERROR)
+        assert "#ret#" in res.reason
+        assert res.reason["#ret#"].value == context.sheerka.newn(BuiltinConcepts.UNKNOWN_CONCEPT, requested="bar")
+
+    def test_i_cannot_evaluate_when_error(self, context, service):
+        with NewOntology(context, "test_i_cannot_evaluate_when_error"):
+            foo, = get_concepts(context,
+                                get_concept("foo", body="I am a concept"),  # "one" does not exist
+                                use_sheerka=True)
+
+            res = service.evaluate_concept(context, foo)
+
+            assert context.sheerka.isinstance(res, BuiltinConcepts.INVALID_CONCEPT)
+
diff --git a/tests/services/test_ConceptManager.py b/tests/services/test_ConceptManager.py
index ee32ed8..8822aec 100644
--- a/tests/services/test_ConceptManager.py
+++ b/tests/services/test_ConceptManager.py
@@ -6,8 +6,8 @@ from conftest import NewOntology
 from core.BuiltinConcepts import BuiltinConcepts
 from core.concept import ConceptMetadata
 from core.error import ErrorContext
-from helpers import get_concepts, get_metadata
-from services.SheerkaConceptManager import ConceptAlreadyDefined, ConceptManager
+from helpers import get_concept, get_concepts, get_metadata
+from services.SheerkaConceptManager import ConceptAlreadyDefined, ConceptManager, ConceptRef
 
 
 class TestConceptManager(BaseTest):
@@ -86,7 +86,7 @@ class TestConceptManager(BaseTest):
             assert metadata.name == "name"
             assert metadata.key == "name"
             assert metadata.body == "body"
-            assert metadata.digest == "c75faa4efbc9ef9dbc5174c52786d5b066e2ece41486b81c27336e292917fecb"
+            assert metadata.digest == "f32363f42e698b1642c8f76f969d76d56f53f0e0732cb651e3360e3ede7b2b11"
             assert metadata.all_attrs == ('#where#', '#pre#', '#post#', '#body#', '#ret#')
 
             # is sorted in db
@@ -96,6 +96,60 @@ class TestConceptManager(BaseTest):
             assert om.get(ConceptManager.CONCEPTS_BY_KEY_ENTRY, metadata.key) == metadata
             assert om.get(ConceptManager.CONCEPTS_BY_HASH_ENTRY, metadata.digest) == metadata
 
+            # check first token
+            assert om.get(ConceptManager.CONCEPT_BY_FIRST_TOKEN_IN_KEY, "name") == ["1001"]
+
+    def test_i_can_define_a_new_concept_with_variables(self, context, service):
+        with NewOntology(context, "test_i_can_define_a_new_concept_with_variables"):
+            res = service.define_new_concept(context,
+                                             name="a multiplied by b",
+                                             variables=[("a", NotInit), ("b", NotInit)])
+
+            metadata = res.value.metadata
+            assert isinstance(metadata, ConceptMetadata)
+            assert metadata.id == "1001"
+            assert metadata.name == "a multiplied by b"
+            assert metadata.key == "__var__0 multiplied by __var__1"
+            assert metadata.digest == "17d2360d82fc4264e2bcb75e4aa30ee3de87531acee72f5d939e23bff246b2dd"
+            assert metadata.all_attrs == ('#where#', '#pre#', '#post#', '#body#', '#ret#', "a", "b")
+
+            # is sorted in db
+            om = context.sheerka.om
+            assert om.get(ConceptManager.CONCEPTS_BY_ID_ENTRY, metadata.id) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_NAME_ENTRY, metadata.name) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_KEY_ENTRY, metadata.key) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_HASH_ENTRY, metadata.digest) == metadata
+
+            # check first token
+            assert om.get(ConceptManager.CONCEPT_BY_FIRST_TOKEN_IN_KEY, "multiplied") == ["1001"]
+
+    def test_i_can_define_a_new_concept_using_definition(self, context, service):
+        with NewOntology(context, "test_i_can_define_a_new_concept_using_definition"):
+            res = service.define_new_concept(context,
+                                             name="multiplication",
+                                             definition="a multiplied by b",
+                                             variables=[("a", NotInit), ("b", NotInit)])
+
+            metadata = res.value.metadata
+            assert isinstance(metadata, ConceptMetadata)
+            assert metadata.id == "1001"
+            assert metadata.name == "multiplication"
+            assert metadata.definition == "a multiplied by b"
+            assert metadata.key == "__var__0 multiplied by __var__1"
+            assert metadata.digest == "b29007ea67bddc48329a2ae0124a320e26c86fb6b106aad6581bc75dfdf5ebeb"
+            assert metadata.all_attrs == ('#where#', '#pre#', '#post#', '#body#', '#ret#', "a", "b")
+
+            # is sorted in db
+            om = context.sheerka.om
+            assert om.get(ConceptManager.CONCEPTS_BY_ID_ENTRY, metadata.id) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_NAME_ENTRY, metadata.name) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_KEY_ENTRY, metadata.key) == metadata
+            assert om.get(ConceptManager.CONCEPTS_BY_HASH_ENTRY, metadata.digest) == metadata
+
+            # check first token
+            assert om.get(ConceptManager.CONCEPT_BY_FIRST_TOKEN_IN_KEY, "multiplied") == ["1001"]
+            assert om.get(ConceptManager.CONCEPT_BY_FIRST_TOKEN_IN_NAME, "multiplication") == ["1001"]
+
     def test_i_cannot_create_the_same_concept_twice(self, context, service):
         with NewOntology(context, "test_i_cannot_create_the_same_concept_twice"):
             res = service.define_new_concept(context, "name", body="body")
@@ -176,11 +230,11 @@ class TestConceptManager(BaseTest):
     def test_i_cannot_instantiate_a_concept_which_does_not_exist(self, context, service):
         foo = service.newn("foo", var1="value1", var2="value2")
         assert foo.key == BuiltinConcepts.UNKNOWN_CONCEPT
-        assert foo.requested_name == "foo"
+        assert foo.requested == "foo"
 
         foo = service.newi("1001", var1="value1", var2="value2")
         assert foo.key == BuiltinConcepts.UNKNOWN_CONCEPT
-        assert foo.requested_id == "1001"
+        assert foo.requested == "#1001"
 
     def test_i_can_instantiate_by_name_when_multiple_results(self, context, service):
         with NewOntology(context, "test_i_can_instantiate_by_name_when_multiple_results"):
@@ -255,6 +309,48 @@ class TestConceptManager(BaseTest):
             assert context.sheerka.isinstance(res[0], foo)
             assert context.sheerka.isinstance(res[1], bar)
 
+    def test_i_can_new_using_concept_reference(self, context, service):
+        with NewOntology(context, "test_i_can_new_using_concept_reference"):
+            foo, bar, baz = get_concepts(context, "foo", "bar", "baz", use_sheerka=True)
+
+            foo.get_runtime_info().info["resolution_method"] = "id"
+            bar.get_runtime_info().info["resolution_method"] = "key"
+
+            foo_concept_ref = ConceptRef(foo)
+            res = service.new(foo_concept_ref)
+            assert context.sheerka.isinstance(res, foo)
+
+            bar_concept_ref = ConceptRef(bar)
+            res = service.new(bar_concept_ref)
+            assert context.sheerka.isinstance(res, bar)
+
+            baz_concept_ref = ConceptRef(baz)
+            res = service.new(baz_concept_ref)
+            assert context.sheerka.isinstance(res, baz)
+
+    def test_i_can_new_using_concept_reference_when_multiple_results(self, context, service):
+        with NewOntology(context, "test_i_can_new_using_concept_reference"):
+            foo1, foo2 = get_concepts(context,
+                                      get_concept("foo", body="1"),
+                                      get_concept("foo", body="2"),
+                                      use_sheerka=True)
+
+            foo = get_concept("foo")  # blueprint, no need to be known by Sheerka
+            foo.get_runtime_info().info["resolution_method"] = "name"
+            foo_concept_ref = ConceptRef(foo)
+
+            res = service.new(foo_concept_ref)
+            assert res == [foo1, foo2]
+
+    def test_i_cannot_new_using_concept_reference_when_unknown(self, context, service):
+        foo = get_concept("foo")  # not known by Sheerka
+        foo.get_runtime_info().info["resolution_method"] = "name"
+
+        foo_concept_ref = ConceptRef(foo)
+        res = service.new(foo_concept_ref)
+        assert context.sheerka.isinstance(res, BuiltinConcepts.UNKNOWN_CONCEPT)
+        assert res.requested == "foo"
+
     def test_unknown_concept_is_return_if_the_identifier_is_not_found(self, service):
         assert service.new("unknown").name == BuiltinConcepts.UNKNOWN_CONCEPT
 
diff --git a/tests/services/test_SheerkaDummyEventManager.py b/tests/services/test_SheerkaDummyEventManager.py
new file mode 100644
index 0000000..3c56a6f
--- /dev/null
+++ b/tests/services/test_SheerkaDummyEventManager.py
@@ -0,0 +1,66 @@
+import pytest
+
+from base import BaseTest
+from services.SheerkaDummyEventManager import SheerkaDummyEventManager
+
+
+def example_of_function(context):
+    print(f"example_of_class_method. event={context.event.get_digest()}")
+
+
+def example_of_function_with_data(context, data):
+    print(f"example_of_class_method. event={context.event.get_digest()}, {data=}")
+
+
+class TestSheerkaEventManager(BaseTest):
+
+    @pytest.fixture()
+    def service(self, sheerka):
+        service = sheerka.services[SheerkaDummyEventManager.NAME]
+        yield service
+
+        service.test_only_reset_service()
+
+    def example_of_class_method(self, context):
+        print(f"example_of_class_method. event={context.event.get_digest()}")
+
+    @staticmethod
+    def example_of_static_method(context):
+        print(f"example_of_static_method. event={context.event.get_digest()}")
+
+    def example_of_class_method_with_data(self, context, data):
+        print(f"example_of_class_method. event={context.event.get_digest()}, {data=}")
+
+    @staticmethod
+    def example_of_static_method_with_data(context, data):
+        print(f"example_of_static_method. event={context.event.get_digest()}, {data=}")
+
+    def test_i_can_subscribe_and_publish(self, context, service, capsys):
+        topic = "my topic"
+
+        service.subscribe(topic, self.example_of_class_method)
+        service.subscribe(topic, self.example_of_static_method)
+        service.subscribe(topic, example_of_function)
+
+        service.publish(context, topic)
+
+        captured = capsys.readouterr()
+        assert captured.out == """example_of_class_method. event=xxx
+example_of_static_method. event=xxx
+example_of_class_method. event=xxx
+"""
+
+    def test_i_can_subscribe_and_publish_with_data(self, context, service, capsys):
+        topic = "my topic"
+
+        service.subscribe(topic, self.example_of_class_method_with_data)
+        service.subscribe(topic, self.example_of_static_method_with_data)
+        service.subscribe(topic, example_of_function_with_data)
+
+        service.publish(context, topic, "42")
+
+        captured = capsys.readouterr()
+        assert captured.out == """example_of_class_method. event=xxx, data='42'
+example_of_static_method. event=xxx, data='42'
+example_of_class_method. event=xxx, data='42'
+"""
diff --git a/tests/services/test_SheerkaPython.py b/tests/services/test_SheerkaPython.py
index 745db97..ddd8fcc 100644
--- a/tests/services/test_SheerkaPython.py
+++ b/tests/services/test_SheerkaPython.py
@@ -1,3 +1,5 @@
+import ast
+
 import pytest
 
 from base import BaseTest, DummyObj
@@ -7,11 +9,13 @@ from core.BuiltinConcepts import BuiltinConcepts
 from core.ExecutionContext import ContextActions
 from core.concept import ConceptDefaultProps
 from core.error import MethodAccessError
+from core.python_fragment import PythonFragment
 from evaluators.PythonParser import PythonParser
-from helpers import _rv, define_new_concept, get_concepts, get_evaluated_concept, get_metadata
+from helpers import _rv, define_new_concept, get_concepts, get_evaluated_concept, get_evaluated_concepts, get_metadata
 from parsers.ParserInput import ParserInput
 from parsers.tokenizer import Token, TokenKind
-from services.SheerkaPython import EvalMethod, EvaluationContext, EvaluationRef, Expando, MultipleResults, SheerkaPython
+from services.SheerkaConceptManager import ConceptRef
+from services.SheerkaPython import EvalMethod, EvaluationContext, Expando, MultipleResults, ObjectRef, SheerkaPython
 
 
 def get_python_fragment(sheerka, context, command):
@@ -70,7 +74,7 @@ class TestSheerkaPython(BaseTest):
 
     def test_i_can_eval_using_eval_ref(self, sheerka, context, service):
         python_fragment = get_python_fragment(sheerka, context, "a")
-        python_fragment.namespace = {"a": EvaluationRef("self", "a")}
+        python_fragment.namespace = {"a": ObjectRef("self", "a")}
 
         ret = service.evaluate_python(context, EvaluationContext(), python_fragment,
                                       {"self": DummyObj("my dummy value")})
@@ -95,6 +99,38 @@ class TestSheerkaPython(BaseTest):
             ret = service.evaluate_python(context, EvaluationContext(), python_fragment)
             assert ret == 3
 
+    def test_i_can_eval_when_multiple_concepts(self, sheerka, context, service):
+        with NewOntology(context, "test_i_can_eval_when_multiple_concepts"):
+            get_concepts(context,
+                         get_metadata("one", body="'one'"),
+                         get_metadata("one", body="1"),
+                         use_sheerka=True)
+            python_fragment = get_python_fragment(sheerka, context, "one + 1")
+
+            ret = service.evaluate_python(context, EvaluationContext(), python_fragment)
+
+            assert ret == 2
+
+    def test_i_can_eval_when_multiple_result_in_local_namespace(self, sheerka, context, service):
+        # In the test, the PythonFragment contains a MultipleResult in its namespace
+        # (normally, the MultipleResult is created inside the evaluate_python)
+        # We need to make sure that multiple results are created in the same way
+        with NewOntology(context, "test_i_can_eval_when_multiple_result_in_local_namespace"):
+            one1, one2 = get_concepts(context,
+                                      get_metadata("one", body="'one'"),
+                                      get_metadata("one", body="1"),
+                                      use_sheerka=True)
+
+            concept_ref = "__concept_id__"
+            ast_tree = ast.parse(concept_ref, "", 'eval')
+            ref = MultipleResults(ConceptRef(one1), ConceptRef(one2))
+            python_fragment = PythonFragment(concept_ref, ast_tree=ast_tree, namespace={concept_ref: ref})
+
+            ret = service.evaluate_python(context, EvaluationContext(eval_method=EvalMethod.All), python_fragment)
+
+            evaluated_one1, evaluated_one2 = get_evaluated_concepts(context, one1, one2, use_sheerka=True)
+            assert ret == MultipleResults(evaluated_one1, "one", evaluated_one2, 1)
+
     def test_i_can_remember_previous_results(self, sheerka, context, service):
         python_fragment = get_python_fragment(sheerka, context, "a=10")
         ret = service.evaluate_python(context, EvaluationContext(), python_fragment)
@@ -151,18 +187,6 @@ class TestSheerkaPython(BaseTest):
                                           get_evaluated_concept(foo_3, body='bar'),
                                           "bar")
 
-    def test_i_can_eval_when_multiple_concepts(self, sheerka, context, service):
-        with NewOntology(context, "test_i_can_eval_when_multiple_concepts"):
-            get_concepts(context,
-                         get_metadata("one", body="'one'"),
-                         get_metadata("one", body="1"),
-                         use_sheerka=True)
-            python_fragment = get_python_fragment(sheerka, context, "one + 1")
-
-            ret = service.evaluate_python(context, EvaluationContext(), python_fragment)
-
-            assert ret == 2
-
     def test_i_can_eval_until_a_successful_result_is_found(self, sheerka, context, service):
         with NewOntology(context, "test_i_can_eval_when_multiple_concepts"):
             get_concepts(context,
@@ -338,3 +362,10 @@ class TestSheerkaPython(BaseTest):
         foo, bar = get_concepts(context, "foo", "bar")
         assert MultipleResults(foo, "one", bar, 1).concepts_only() == MultipleResults(foo, bar)
         assert MultipleResults("one", 1).concepts_only() == MultipleResults()
+
+    def test_i_can_add_multiple_results_of_multiple_results(self, context):
+        foo, bar, baz, qux = get_concepts(context, "foo", "bar", "baz", "qux")
+        m1 = MultipleResults(foo, bar)
+        m2 = MultipleResults(bar, baz, m1)
+
+        assert m2.items == [bar, baz, foo, bar]
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 1b4f6d7..394318d 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -2,7 +2,8 @@ import pytest
 
 from common.global_symbols import NotInit
 from core.concept import Concept, ConceptDefaultProps, ConceptMetadata, DefinitionType
-from helpers import GetNextId, get_concept, get_concepts, get_metadata, get_metadatas, get_evaluated_concept
+from helpers import GetNextId, _mt, _ut, get_concept, get_concepts, get_evaluated_concept, get_from, get_metadata, \
+    get_metadatas
 
 
 def test_i_can_get_default_value_when_get_metadata():
@@ -233,7 +234,7 @@ def test_i_can_get_multiple_concepts_when_same_name(sheerka, context):
     assert sheerka.isinstance(one_int, "one")
 
 
-def test_i_can_create_test_concept(sheerka, context):
+def test_i_can_create_test_concept():
     concept = get_concept("one", body="'one'")
 
     test_concept = get_evaluated_concept(concept, body='hello', a="value for a")
@@ -241,3 +242,39 @@ def test_i_can_create_test_concept(sheerka, context):
     assert test_concept.get_metadata() == concept.get_metadata()
     assert test_concept.get_value(ConceptDefaultProps.BODY) == "hello"
     assert test_concept.get_value("a") == "value for a"
+
+
+def test_i_can_dummy_evaluate_concept():
+    concept = get_concept("one", body="'one'", where="True", pre="False", ret="1", post="1.0")
+
+    evaluated = get_evaluated_concept(concept)
+    assert evaluated.get_value(ConceptDefaultProps.WHERE) is True
+    assert evaluated.get_value(ConceptDefaultProps.PRE) is False
+    assert evaluated.get_value(ConceptDefaultProps.BODY) == "one"
+    assert evaluated.get_value(ConceptDefaultProps.RET) == 1
+    assert evaluated.get_value(ConceptDefaultProps.POST) == 1.0
+
+    concept = get_concept("one", body='"one"', ret="'a value'")
+    evaluated = get_evaluated_concept(concept, ret='forced value')
+    assert evaluated.get_value(ConceptDefaultProps.WHERE) == NotInit
+    assert evaluated.get_value(ConceptDefaultProps.PRE) == NotInit
+    assert evaluated.get_value(ConceptDefaultProps.BODY) == "one"
+    assert evaluated.get_value(ConceptDefaultProps.RET) == "forced value"
+    assert evaluated.get_value(ConceptDefaultProps.POST) == NotInit
+
+
+def test_i_can_get_from():
+    res = get_from(_mt("c:i am a concept#1001:"))
+    assert res == [_mt("1001", 0, 6)]
+
+    res = get_from(_ut("some unrecognized stuff"))
+    assert res == [_ut("some unrecognized stuff", 0, 4)]
+
+    res = get_from(_mt("c:i am a concept#1001:"), _ut("some unrecognized stuff"))
+    assert res == [_mt("1001", 0, 6), _ut("some unrecognized stuff", 7, 11)]
+
+    res = get_from(_mt("c:i am a concept#1001:"), _ut("some unrecognized stuff"), parser="other")
+    assert res == [_mt("1001", 0, 6, parser="other"), _ut("some unrecognized stuff", 7, 11)]
+
+    res = get_from(_mt("c:i am a concept#1001:"), _mt("c:#1001:"))
+    assert res == [_mt("1001", 0, 6), _mt("1001", 7, 13)]