text:   if (!!root.Set) {
      /**
       * Converts the observable sequence to a Set if it exists.
       * @returns {Observable} An observable sequence with a single value of a Set containing the values from the observable sequence.
       */
      observableProto.toSet = function () {
        var source = this;
        return new AnonymousObservable(function (observer) {
          var s = new root.Set();
          return source.subscribe(
            s.add.bind(s),
            observer.onError.bind(observer),
            function () {
              observer.onNext(s);
              observer.onCompleted();
            });
        });
      };
    }
  