public static Observable<Void> mapToVoid(Observable<?> fromObservable) {
        if (fromObservable != null) {
            return fromObservable.subscribeOn(Schedulers.io())
                    .map(new RXMapper<Void>());
        } else {
            return Observable.empty();
        }
    }
public static Observable < Void > mapToVoid ( Observable < ? > fromObservable ) { if ( fromObservable != null ) { return fromObservable . subscribeOn ( Schedulers . io ( ) ) . map ( new RXMapper < Void > ( ) ) ; } else { return Observable . empty ( ) ; } }
Shortcut for mapping an arbitrary observable to void, using the IO scheduler.
@param fromObservable the source observable
@return a void-emitting observable