code: public static <T> LatchedObserver<T> create(Action1<? super T> onNext, Action1<? super Throwable> onError, CountDownLatch latch) {
          return new LatchedObserverImpl<T>(onNext, onError, Functionals.empty(), latch);
      }
docs: Create a LatchedObserver with the given callback function(s) and a shared latch.