  var Observable = Rx.Observable,
    CompositeDisposable = Rx.CompositeDisposable,
    RefCountDisposable = Rx.RefCountDisposable,
    SingleAssignmentDisposable = Rx.SingleAssignmentDisposable,
    SerialDisposable = Rx.SerialDisposable,
    Subject = Rx.Subject,
    observableProto = Observable.prototype,
    observableEmpty = Observable.empty,
    observableNever = Observable.never,
    AnonymousObservable = Rx.AnonymousObservable,
    observerCreate = Rx.Observer.create,
    addRef = Rx.internals.addRef,
    defaultComparer = Rx.internals.isEqual,
    noop = Rx.helpers.noop,
    identity = Rx.helpers.identity;
  