code: def _establish_connection(self, conn: BrokerConnection) -> None:
          
          try:
              self._logger.debug("Establishing connection.")
              self._conn = conn.ensure_connection(max_retries=3)
              self._logger.debug('Got connection: %s', conn.as_uri())
          except kombu_exceptions.OperationalError as oe:
              self._logger.error("Error connecting to RMQ, could not retry %s", oe)
              # Try to clean up the mess
              if self._conn is not None:
                  self._conn.close()
              else:
                  conn.close()
docs: We don't use a pool here. We only have one consumer connection per process, so
          we get no value from a pool, and we want to use a heartbeat to keep the consumer
          collection alive, which does not work with a pool
          :return: the connection to the transport