docs: def _start_timeout():
      """Stop a running timeout if it's there, then create a new one."""
      global _timeout
  
      LOGGER.debug('Adding a new timeout in %i ms', _timeout_interval)
      _maybe_stop_timeout()
      _timeout = ioloop.IOLoop.current().add_timeout(
          ioloop.IOLoop.current().time() + _timeout_interval / 1000.0,
          _on_timeout)