@CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Observable<T> generate(final Consumer<Emitter<T>> generator) {
        ObjectHelper.requireNonNull(generator, "generator is null");
        return generate(Functions.<Object>nullSupplier(),
        ObservableInternalHelper.simpleGenerator(generator), Functions.<Object>emptyConsumer());
    }