code: async def _relay(self,
                       channel: aioamqp.channel.Channel,
                       body: str,
                       envelope: aioamqp.envelope.Envelope,
                       properties: aioamqp.properties.Properties):
          
          try:
              await channel.basic_client_ack(envelope.delivery_tag)
              await self.on_message(self, envelope.routing_key, json.loads(body))
          except Exception as ex:
              LOGGER.error(f'Exception relaying message in {self}: {ex}')
docs: Relays incoming messages between the queue and the user callback