code: def _on_connection_open(self, connection):
          
          _log.info("Successfully opened connection to %s", connection.params.host)
          self._channel = connection.channel(on_open_callback=self._on_channel_open)
docs: Callback invoked when the connection is successfully established.
  
          Args:
              connection (pika.connection.SelectConnection): The newly-estabilished
                  connection.