@Override
public Subscriber<? super Observable<? extends T>> call(Subscriber<? super T> child) {
final SerializedSubscriber<T> s = new SerializedSubscriber<T>(child);
final CompositeSubscription csub = new CompositeSubscription();
child.add(csub);
SourceSubscriber<T> ssub = new SourceSubscriber<T>(maxConcurrency, s, csub);
child.setProducer(new MergeMaxConcurrentProducer<T>(ssub));
return ssub;
}
