/**
   *  Returns a specified number of contiguous elements from the start of an observable sequence, using the specified scheduler for the edge case of take(0).
   *
   *  var res = source.take(5);
   *  var res = source.take(0, Rx.Scheduler.timeout);
   * @param {Number} count The number of elements to return.
   * @param {Scheduler} [scheduler] Scheduler used to produce an OnCompleted message in case <paramref name="count count</paramref> is set to 0.
   * @returns {Observable} An observable sequence that contains the specified number of elements from the start of the input sequence.
   */
  observableProto.take = function (count, scheduler) {
    if (count < 0) { throw new RangeError(argumentOutOfRange); }
    if (count === 0) { return observableEmpty(scheduler); }
    var source = this;
    return new AnonymousObservable(function (o) {
      var remaining = count;
      return source.subscribe(function (x) {
        if (remaining-- > 0) {
          o.onNext(x);
          remaining === 0 && o.onCompleted();
        }
      }, function (e) { o.onError(e); }, function () { o.onCompleted(); });
    }, source);
  };