reactor-core/src/main/java/reactor/core/publisher/ParallelFlux.java
@Override
	@SuppressWarnings("unchecked")
	public final void subscribe(Subscriber<? super T> s) {
		FluxHide.SuppressFuseableSubscriber<T> subscriber =
				new FluxHide.SuppressFuseableSubscriber<>(Operators.toCoreSubscriber(s));

		Operators.onLastAssembly(sequential()).subscribe(Operators.toCoreSubscriber(subscriber));
	}
@Override
	@SuppressWarnings("unchecked")
	public final void subscribe(Subscriber<? super T> s) {
		FluxHide.SuppressFuseableSubscriber<T> subscriber =
				new FluxHide.SuppressFuseableSubscriber<>(Operators.toCoreSubscriber(s));

		Operators.onLastAssembly(sequential()).subscribe(Operators.toCoreSubscriber(subscriber));
	}
Merge the rails into a {@link #sequential()} Flux and
{@link Flux#subscribe(Subscriber) subscribe} to said Flux.

@param s the subscriber to use on {@link #sequential()} Flux