_fixReplyParameters(obj) {
    if (obj.hasOwnProperty('reply_parameters') && typeof obj.reply_parameters !== 'string') {
      obj.reply_parameters = stringify(obj.reply_parameters);
    }
  }
Fix 'reply_parameters' parameter by making it JSON-serialized, as
required by the Telegram Bot API
@param {Object} obj Object; either 'form' or 'qs'
@private
@see https://core.telegram.org/bots/api#sendmessage