function observe(obj, callback) {
    var patches = [];
    var observer;
    var mirror = getMirror(obj);
    if (!mirror) {
        mirror = new Mirror(obj);
        beforeDict.set(obj, mirror);
    }
    else {
        var observerInfo = getObserverFromMirror(mirror, callback);
        observer = observerInfo && observerInfo.observer;
    }
    if (observer) {
        return observer;
    }
    observer = {};
    mirror.value = helpers_js_1._deepClone(obj);
    if (callback) {
        observer.callback = callback;
        observer.next = null;
        var dirtyCheck = function () {
            generate(observer);
        };
        var fastCheck = function () {
            clearTimeout(observer.next);
            observer.next = setTimeout(dirtyCheck);
        };
        if (typeof window !== 'undefined') { //not Node
            window.addEventListener('mouseup', fastCheck);
            window.addEventListener('keyup', fastCheck);
            window.addEventListener('mousedown', fastCheck);
            window.addEventListener('keydown', fastCheck);
            window.addEventListener('change', fastCheck);
        }
    }
    observer.patches = patches;
    observer.object = obj;
    observer.unobserve = function () {
        generate(observer);
        clearTimeout(observer.next);
        removeObserverFromMirror(mirror, observer);
        if (typeof window !== 'undefined') {
            window.removeEventListener('mouseup', fastCheck);
            window.removeEventListener('keyup', fastCheck);
            window.removeEventListener('mousedown', fastCheck);
            window.removeEventListener('keydown', fastCheck);
            window.removeEventListener('change', fastCheck);
        }
    };
    mirror.observers.set(callback, new ObserverInfo(callback, observer));
    return observer;
}
Observes changes made to an object, which can then be retrieved using generate