code: public static <T> Observable.Transformer<T, T> applySchedulers(final Scheduler subscribeScheduler) {
          return new Observable.Transformer<T, T>() {
              @Override
              public Observable<T> call(Observable<T> observable) {
                  return observable.subscribeOn(subscribeScheduler)
                          .observeOn(AndroidSchedulers.mainThread());
              }
          };
      }
docs: <p>
  Apply the subscribeOn/observeOn transformation of custom/mainThread
  to an observable via compose()
  </p>
  
  @param <T>       the transformation type
  @return          the observable post-transform