constructor(bot) {
    this.bot = bot;
    this.options = (typeof bot.options.polling === 'boolean') ? {} : bot.options.polling;
    this.options.interval = (typeof this.options.interval === 'number') ? this.options.interval : 300;
    this.options.params = (typeof this.options.params === 'object') ? this.options.params : {};
    this.options.params.offset = (typeof this.options.params.offset === 'number') ? this.options.params.offset : 0;
    this.options.params.timeout = (typeof this.options.params.timeout === 'number') ? this.options.params.timeout : 10;
    if (typeof this.options.timeout === 'number') {
      deprecate('`options.polling.timeout` is deprecated. Use `options.polling.params` instead.');
      this.options.params.timeout = this.options.timeout;
    }
    this._lastUpdate = 0;
    this._lastRequest = null;
    this._abort = false;
    this._pollingTimeout = null;
  }
Handles polling against the Telegram servers.
@param  {TelegramBot} bot
@see https://core.telegram.org/bots/api#getting-updates