promoteChatMember(chatId, userId, form = {}) {
    form.chat_id = chatId;
    form.user_id = userId;
    return this._request('promoteChatMember', { form });
  }
Use this method to promote or demote a user in a supergroup or a channel.
The bot **must be an administrator** in the chat for this to work
and must have the appropriate admin rights. Pass False for all boolean parameters to demote a user.

@param {Number|String} chatId  Unique identifier for the target chat or username of the target channel (in the format `@channelusername`)
@param {Number} userId
@param {Object} [options] Additional Telegram query options
@return {Promise} True on success.
@see https://core.telegram.org/bots/api#promotechatmember