code: @CheckReturnValue
      @SchedulerSupport(SchedulerSupport.NONE)
      @SuppressWarnings("unchecked")
      public final Single<T> ambWith(SingleSource<? extends T> other) {
          ObjectHelper.requireNonNull(other, "other is null");
          return ambArray(this, other);
      }
docs: Signals the event of this or the other SingleSource whichever signals first.
  <p>
  <img width="640" height="463" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Single.ambWith.png" alt="">
  <dl>
  <dt><b>Scheduler:</b></dt>
  <dd>{@code ambWith} does not operate by default on a particular {@link Scheduler}.</dd>
  </dl>
  @param other the other SingleSource to race for the first emission of success or error
  @return the new Single instance. A subscription to this provided source will occur after subscribing
  to the current source.
  @since 2.0