Reactive-Extensions/RxJS

/// <reference path="./disposables/disposable.ts" />
module Rx {
    export interface Observer<T> {
        makeSafe(disposable: IDisposable): Observer<T>;
    }
}
 
(function() {
    var observer: Rx.Observer<boolean>;
    observer = observer.makeSafe(Rx.Disposable.create(() => {}));
});