anchor.diff:          { $identifier = $typeReference.identifier;
             $typeArgumentList = $typeReference.typeArgumentList; 
             $isMember=false; }
  -      |
  +      | (~(LIDENTIFIER|UIDENTIFIER))=>
           { displayRecognitionError(getTokenNames(), 
                 new MismatchedTokenException(LIDENTIFIER, input)); }
         )
  
positive.code:       expression
        { $positionalArgument = new PositionalArgument(null);
          $positionalArgument.setExpression($expression.expression); }
      ;
      
  assignmentExpression returns [Term term]
  
negative.code: namedArguments returns [NamedArgumentList namedArgumentList]
      : LBRACE 
        { $namedArgumentList = new NamedArgumentList($LBRACE); }
        ( //TODO: get rid of the predicate and use the approach
          //      in expressionOrSpecificationStatement
          (namedArgumentStart) 
          => namedArgument
          { if ($namedArgument.namedArgument!=null) 
  