code: def get_sendback(self, uuid, key):
          
          def send_back_callback(data):
              self.sendResponse(
                  serializers.serialize(data),
                  uuid,
                  key
              )
  
          return send_back_callback
docs: Return function for sending progress messages back to original caller.
  
          Args:
              uuid (str): UUID of the received message.
              key (str): Routing key.
  
          Returns:
              fn reference: Reference to function which takes only one data \
                            argument.