anchor.diff:  value_method
       : (loc_id=LOCAL_ID | value_id=id | eventdata=EVENTDATA | query=query_method | '(' subquery ')') '.' call=value_call
       ;
  -    
  +
   value_call
       :  VALUE '(' xquery=STRING ',' sqltype=STRING ')'
       ;
  
positive.code: exist_call
      : EXIST '(' xquery=STRING ')'
      ;
      
  modify_method
      : (loc_id=LOCAL_ID | value_id=id | '(' subquery ')') '.' call=modify_call
      ;
  
negative.code: 
  file_size
      : DECIMAL( KB | MB | GB | TB | '%' )?
      ;
  