code: public static <R> Observable<R> fromRunnable(final Runnable run, final R result) {
          return fromRunnable(run, result, Schedulers.computation());
      }
docs: Return an Observable that calls the given Runnable and emits the given result when an Observer
  subscribes.
  <p>
  <img width="640" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/fromRunnable.png" alt="">
  <p>
  The Runnable is called on the default thread pool for computation.
  
  @param <R> the return type
  @param run the runnable to invoke on each subscription
  @param result the result to emit to observers
  @return an Observable that calls the given Runnable and emits the given result when an Observer
  subscribes
  @see <a href="https://github.com/ReactiveX/RxJava/wiki/Async-Operators#wiki-fromrunnable">RxJava Wiki: fromRunnable()</a>