code: def _broker_exit(self):
          
          for _, (side, _) in self.poller.readers + self.poller.writers:
              LOG.debug('_broker_main() force disconnecting %r', side)
              side.stream.on_disconnect(self)
  
          self.poller.close()
docs: Forcefully call :meth:`Stream.on_disconnect` on any streams that failed
          to shut down gracefully, then discard the :class:`Poller`.