code: def connect(self):
          
          self._logger.info('Connecting to %s' % self._url)
          return adapters.TornadoConnection(pika.URLParameters(self._url),
                                            self.on_connection_open,
                                            custom_ioloop=self._ioloop_instance)
docs: This method connects to RabbitMQ, returning the connection handle.
          When the connection is established, the on_connection_open method
          will be invoked by pika.
  
          :rtype: pika.SelectConnection