@BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    @CheckReturnValue
    @NonNull
    public final Flowable<T> sequentialDelayError(int prefetch) {
        ObjectHelper.verifyPositive(prefetch, "prefetch");
        return RxJavaPlugins.onAssembly(new ParallelJoin<T>(this, prefetch, true));
    }