@CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U, V> Flowable<T> delay(Publisher<U> subscriptionIndicator,
            Function<? super T, ? extends Publisher<V>> itemDelayIndicator) {
        return delaySubscription(subscriptionIndicator).delay(itemDelayIndicator);
    }