src/main/java/io/reactivex/Maybe.java
@SchedulerSupport(SchedulerSupport.NONE)
    public final Disposable subscribe() {
        return subscribe(Functions.emptyConsumer(), Functions.ON_ERROR_MISSING, Functions.EMPTY_ACTION);
    }
@SchedulerSupport(SchedulerSupport.NONE)
    public final Disposable subscribe() {
        return subscribe(Functions.emptyConsumer(), Functions.ON_ERROR_MISSING, Functions.EMPTY_ACTION);
    }
Subscribes to a Maybe and ignores {@code onSuccess} and {@code onComplete} emissions.
<p>
If the Maybe emits an error, it is wrapped into an
{@link io.reactivex.exceptions.OnErrorNotImplementedException OnErrorNotImplementedException}
and routed to the RxJavaPlugins.onError handler.
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code subscribe} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@return a {@link Disposable} reference with which the caller can stop receiving items before
the Maybe has finished sending them
@see <a href="http://reactivex.io/documentation/operators/subscribe.html">ReactiveX operators documentation: Subscribe</a>