Fixed concept token parsing

src/core/sheerka/services/SheerkaSetsManager.py

@@ -150,12 +150,7 @@ class SheerkaSetsManager(BaseService):
         :return:
         """
 
-        if isinstance(a, BuiltinConcepts):  # common KSI error ;-)
-            raise SyntaxError("Remember that the first parameter of isinstance MUST be a concept")
-
         ensure_concept(a, b)
-        # if not (isinstance(a, Concept) and isinstance(b, Concept)):
-        #     return False
 
         # TODO, first check the 'isa' property of a
         if not (a.id and b.id):