/**
   *  Generates an observable sequence that repeats the given element the specified number of times, using the specified scheduler to send out observer messages.
   *
   * @example
   *  var res = Rx.Observable.repeat(42);
   *  var res = Rx.Observable.repeat(42, 4);
   *  3 - res = Rx.Observable.repeat(42, 4, Rx.Scheduler.timeout);
   *  4 - res = Rx.Observable.repeat(42, null, Rx.Scheduler.timeout);
   * @param {Mixed} value Element to repeat.
   * @param {Number} repeatCount [Optiona] Number of times to repeat the element. If not specified, repeats indefinitely.
   * @param {Scheduler} scheduler Scheduler to run the producer loop on. If not specified, defaults to Scheduler.immediate.
   * @returns {Observable} An observable sequence that repeats the given element the specified number of times.
   */
  Observable.repeat = function (value, repeatCount, scheduler) {
    isScheduler(scheduler) || (scheduler = currentThreadScheduler);
    return observableReturn(value, scheduler).repeat(repeatCount == null ? -1 : repeatCount);
  };