@CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <R> Flowable<R> concatMapDelayError(Function<? super T, ? extends Publisher<? extends R>> mapper) {
        return concatMapDelayError(mapper, 2, true);
    }