code: async def _handle_conversation_delta(self, conversation):
          
          conv_id = conversation.conversation_id.id
          conv = self._conv_dict.get(conv_id, None)
          if conv is None:
              # Ignore the delta and fetch the complete conversation.
              await self._get_or_fetch_conversation(conv_id)
          else:
              # Update conversation using the delta.
              conv.update_conversation(conversation)
docs: Receive Conversation delta and create or update the conversation.
  
          Args:
              conversation: hangouts_pb2.Conversation instance
  
          Raises:
              NetworkError: A request to fetch the complete conversation failed.