anchor.diff:  
   overriding_function_spec
       : FUNCTION function_name ('(' type_elements_parameter (',' type_elements_parameter)* ')')?
  -      RETURN (type_spec | SELF AS RESULT) 
  +      RETURN (type_spec | SELF AS RESULT)
        (PIPELINED? (IS | AS) (DECLARE? seq_of_declare_specs? body))? ';'?
       ;
   
  
positive.code:     ;
  
  logical_expression
      : multiset_expression (IS NOT?
          (NULL_ | NAN | PRESENT | INFINITE | A_LETTER SET | EMPTY | OF TYPE?
          '(' ONLY? type_spec (',' type_spec)* ')'))*
      | NOT logical_expression
      | logical_expression AND logical_expression
      | logical_expression OR logical_expression
      ;
  
  multiset_expression
  
negative.code: 
  alter_table
      : ALTER TABLE tableview_name
        (
        | alter_table_properties
        | constraint_clauses
        | column_clauses
  