docs: def close(self):
          """Should be closed[explicit] while using external session or connector,
          instead of close by self.__del__."""
          try:
              if not self.session.closed:
                  if self.session._connector_owner:
                      self.session._connector.close()
                  self.session._connector = None
          except Exception as e:
              Config.dummy_logger.error("can not close session for: %s" % e)