docs: def on_message(self, message_id_service, contact_id_service, content):
          """
          To use as callback in message service backend
          """
          try:
              live_chat = Chat.live.get(
                  Q(agent__id_service=contact_id_service) | Q(asker__id_service=contact_id_service))            
          except ObjectDoesNotExist:
              self._new_chat_processing(message_id_service, contact_id_service, content)
          else:
              live_chat.handle_message(message_id_service, contact_id_service, content, self)