I can define and eval BNF definitions

tests/test_DefaultParser.py

@@ -2,13 +2,13 @@ import pytest
 import ast
 
 from core.builtin_concepts import ParserResultConcept, BuiltinConcepts, ReturnValueConcept
-from core.concept import Concept
 from core.sheerka import Sheerka, ExecutionContext
-from parsers.ConceptLexerParser import OrderedChoice, StrMatch, ConceptMatch, RegexParser
+from parsers.ConceptLexerParser import OrderedChoice, StrMatch, ConceptMatch
 from parsers.PythonParser import PythonParser, PythonNode
 from core.tokenizer import Keywords, Tokenizer
 from parsers.DefaultParser import DefaultParser, NameNode, SyntaxErrorNode
 from parsers.DefaultParser import UnexpectedTokenErrorNode, DefConceptNode
+from parsers.BnfParser import BnfParser
 
 
 # def nop():
@@ -341,7 +341,7 @@ def test_i_can_parse_def_concept_from_regex():
     res = parser.parse(get_context(), text)
     node = res.value.value
     definition = OrderedChoice(ConceptMatch("a_concept"), StrMatch("a_string"))
-    parser_result = ParserResultConcept(RegexParser(), "a_concept | 'a_string'", definition, definition)
+    parser_result = ParserResultConcept(BnfParser(), "a_concept | 'a_string'", definition, definition)
     expected = get_concept(name="name", body="__definition[0]", definition=parser_result)
 
     assert res.status