public operator fun CompositeDisposable.plusAssign(d: Disposable) { add(d) }

public Observable<T>.async(): Observable<T> = this.subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread())

public Single<T>.async(): Single<T> = this.subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread())

public Maybe<T>.async(): Maybe<T> = this.subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread())

public Completable.async(): Completable = this.subscribeOn(Schedulers.io())
  .observeOn(AndroidSchedulers.mainThread())