code: function PromiseDecorator(cache) {
    BaseDecorator.call(this, cache);
    this.get = promisify(this.get.bind(this));
    this.set = promisify(this.set.bind(this));
    this.del = promisify(this.del.bind(this));
  }
docs: If no callbacks are provided to
  get, set or del a Promise will
  be returned.