code: function () {
          checkDisposed(this);
          if (this.isStopped) { return; }
          this.isStopped = true;
          for (var i = 0, os = cloneArray(this.observers), len = os.length; i < len; i++) {
            os[i].onCompleted();
          }
  
          this.observers.length = 0;
        }
docs: Notifies all subscribed observers about the end of the sequence.