anchor.diff:      | EXCEPTION
       | EXCEPTION_INIT
       | EXCEPTIONS
  +    | EXISTS
       | EXIT
       | FLOAT
       | FORALL
  
positive.code: drop_index
      : DROP INDEX index_name ';'
      ;
  
  grant_statement
      : GRANT
  
negative.code: function_body
      : FUNCTION identifier ('(' parameter (',' parameter)* ')')?
        RETURN type_spec (invoker_rights_clause | parallel_enable_clause | result_cache_clause | DETERMINISTIC)*
        ((PIPELINED? DETERMINISTIC? (IS | AS) (DECLARE? seq_of_declare_specs? body | call_spec)) | (PIPELINED | AGGREGATE) USING implementation_type_name) ';'
      ;
  
  procedure_body
  