Fixed parsing of BNF concepts mixed with isaset concepts

tests/non_reg/test_sheerka_non_reg.py

@@ -1,6 +1,6 @@
 import pytest
 from core.builtin_concepts import BuiltinConcepts
-from core.concept import Concept, PROPERTIES_TO_SERIALIZE, simplec, CMV
+from core.concept import Concept, PROPERTIES_TO_SERIALIZE, simplec, CMV, NotInit
 from evaluators.MutipleSameSuccessEvaluator import MultipleSameSuccessEvaluator
 from evaluators.PythonEvaluator import PythonEvalError
 from parsers.BaseNodeParser import SyaAssociativity
@@ -319,7 +319,7 @@ as:
         assert res[0].status
         concept_found = res[0].value
         assert sheerka.isinstance(concept_found, greetings)
-        assert concept_found.get_value("a") is None
+        assert concept_found.get_value("a") == NotInit
         assert not concept_found.metadata.need_validation
 
     @pytest.mark.parametrize("desc, definitions", [
@@ -898,8 +898,8 @@ as:
         res = sheerka.evaluate_user_input(expression)
         assert res[0].status
         assert res[0].body == CMV(plus, a="c:one:", b="c:two:")
-        assert res[0].body.a is None  # concept is not evaluated
-        assert res[0].body.b is None  # concept is not evaluated
+        assert res[0].body.a == NotInit  # concept is not evaluated
+        assert res[0].body.b == NotInit  # concept is not evaluated
 
         expression = "eval c:one: < c:two:"
         res = sheerka.evaluate_user_input(expression)