code: def _execute_direct(self, operation):
          
          request = RequestMessage.new(
              self.connection,
              RequestSegment(
                  message_types.EXECUTEDIRECT,
                  Command(operation)
              )
          )
          reply = self.connection.send_request(request)
  
          parts = reply.segments[0].parts
          function_code = reply.segments[0].function_code
          if function_code == function_codes.SELECT:
              self._handle_select(parts)
          elif function_code in function_codes.DML:
              self._handle_upsert(parts)
          elif function_code == function_codes.DDL:
              # No additional handling is required
              pass
          elif function_code in (function_codes.DBPROCEDURECALL, function_codes.DBPROCEDURECALLWITHRESULT):
              self._handle_dbproc_call(parts, None)
          else:
              raise InterfaceError("Invalid or unsupported function code received: %d" % function_code)
docs: Execute statements which are not going through 'prepare_statement' (aka 'direct execution').
          Either their have no parameters, or Python's string expansion has been applied to the SQL statement.
          :param operation: