def semantic_validation(self, error_level: str = "<STR_LIT>") -> "<STR_LIT>":
semantics.validate(self, error_level)<EOL>return self<EOL>
Semantically validate parsed BEL statement

        Run semantics validation - and decorate AST with nsarg entity_type and arg optionality

        Args:
            error_level:  WARNING or ERROR

        Returns:
            BEL: return self