docs: def _maybe_stop_timeout():
      """If there is a pending timeout, remove it from the IOLoop and set the
      ``_timeout`` global to None.
  
      """
      global _timeout
  
      if _timeout is not None:
          LOGGER.debug('Removing the pending timeout (%r)', _timeout)
          ioloop.IOLoop.current().remove_timeout(_timeout)
          _timeout = None