anchor.diff:  
   update_set_clause
       : SET
  -      (column_based_update_set_clause (',' column_based_update_set_clause)* | VALUE '(' identifier ')' '=' expression)
  +      ((','? column_based_update_set_clause)+ | VALUE '(' identifier ')' '=' expression)
       ;
   
   column_based_update_set_clause
       : column_name '=' expression
  -    | '(' column_name (',' column_name)* ')' '=' subquery
  +    | paren_column_list '=' subquery
       ;
   
   delete_statement
  
positive.code: 
  statement
      : CREATE swallow_to_semi
      | ALTER swallow_to_semi
      | GRANT ALL? swallow_to_semi
      | TRUNCATE swallow_to_semi
      | body
      | block
  
negative.code:     ;
  
  rollup_cube_clause
      : (ROLLUP | CUBE) '(' (','? grouping_sets_elements)+ ')'
      ;
  
  grouping_sets_clause
      : GROUPING SETS '(' (','? grouping_sets_elements)+ ')'
      ;
  
  grouping_sets_elements
  