def reactToMessage(self, message_id, reaction):
        """
        Reacts to a message, or removes reaction

        :param message_id: :ref:`Message ID <intro_message_ids>` to react to
        :param reaction: Reaction emoji to use, if None removes reaction
        :type reaction: models.MessageReaction or None
        :raises: FBchatException if request failed
        """
        data = {
            "action": "ADD_REACTION" if reaction else "REMOVE_REACTION",
            "client_mutation_id": "1",
            "actor_id": self._uid,
            "message_id": str(message_id),
            "reaction": reaction.value if reaction else None,
        }
        data = {"doc_id": 1491398900900362, "variables": json.dumps({"data": data})}
        self._post(self.req_url.MESSAGE_REACTION, data, fix_request=True, as_json=True)
Reacts to a message, or removes reaction

        :param message_id: :ref:`Message ID <intro_message_ids>` to react to
        :param reaction: Reaction emoji to use, if None removes reaction
        :type reaction: models.MessageReaction or None
        :raises: FBchatException if request failed