        MultiObserver.Watch = function (observables, callback, mask, scope) {
            if (mask === void 0) { mask = -1; }
            if (scope === void 0) { scope = null; }
            var result = new MultiObserver();
            result._observers = new Array();
            result._observables = observables;
            for (var _i = 0, observables_1 = observables; _i < observables_1.length; _i++) {
                var observable = observables_1[_i];
                result._observers.push(observable.add(callback, mask, false, scope));
            }
            return result;
        };