code: @BackpressureSupport(BackpressureKind.FULL)
      @CheckReturnValue
      @SchedulerSupport(SchedulerSupport.NONE)
      public final <E> Single<T> takeUntil(final Publisher<E> other) {
          ObjectHelper.requireNonNull(other, "other is null");
          return RxJavaPlugins.onAssembly(new SingleTakeUntil<T, E>(this, other));
      }
docs: Returns a Single that emits the item emitted by the source Single until a Publisher emits an item. Upon
  emission of an item from {@code other}, this will emit a {@link CancellationException} rather than go to
  {@link SingleObserver#onSuccess(Object)}.
  <p>
  <img width="640" height="380" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/takeUntil.png" alt="">
  <dl>
  <dt><b>Backpressure:</b></dt>
  <dd>The {@code other} publisher is consumed in an unbounded fashion but will be
  cancelled after the first item it produced.</dd>
  <dt><b>Scheduler:</b></dt>
  <dd>{@code takeUntil} does not operate by default on a particular {@link Scheduler}.</dd>
  </dl>
  
  @param other
  the Publisher whose first emitted item will cause {@code takeUntil} to emit the item from the source
  Single
  @param <E>
  the type of items emitted by {@code other}
  @return a Single that emits the item emitted by the source Single until such time as {@code other} emits
  its first item
  @see <a href="http://reactivex.io/documentation/operators/takeuntil.html">ReactiveX operators documentation: TakeUntil</a>