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

def connect(self):
        """
        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
        """
        self._logger.info('Connecting to %s' % self._url)
        return adapters.TornadoConnection(pika.URLParameters(self._url),
                                          self.on_connection_open,
                                          custom_ioloop=self._ioloop_instance)