public static <T> LatchedObserver<T> create(Action1<? super T> onNext) {
        return create(onNext, new CountDownLatch(1));
    }
public static < T > LatchedObserver < T > create ( Action1 < ? super T > onNext ) { return create ( onNext , new CountDownLatch ( 1 ) ) ; }
Create a LatchedObserver with the given callback function(s).