public static <E, T extends E> Terminable register(EventBus<E> bus, @NonNull final Class<T> clazz, @NonNull final EventSubscriber<? super T> subscriber) {
        bus.register(clazz, subscriber);
        return () -> bus.unregister(subscriber);
    }
Registers the given {@code subscriber} with the {@code bus}, and returns
a {@link Terminable} to encapsulate the subscription.

@param bus the event bus
@param clazz the registration class
@param subscriber the subscriber
@param <E> the event type
@param <T> the subscriber type
@return a terminable to encapsulate the subscription
helper/src/main/java/me/lucko/helper/eventbus/Subscribers.java