src/main/java/io/reactivex/Flowable.java
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.PASS_THROUGH)
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public final Flowable<T> timeout(long timeout, TimeUnit timeUnit) {
        return timeout0(timeout, timeUnit, null, Schedulers.computation());
    }
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.PASS_THROUGH)
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public final Flowable<T> timeout(long timeout, TimeUnit timeUnit) {
        return timeout0(timeout, timeUnit, null, Schedulers.computation());
    }
Returns a Flowable that mirrors the source Publisher but applies a timeout policy for each emitted
item. If the next item isn't emitted within the specified timeout duration starting from its predecessor,
the resulting Publisher terminates and notifies Subscribers of a {@code TimeoutException}.
<p>
<img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/timeout.1.png" alt="">
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The operator doesn't interfere with backpressure which is determined by the source {@code Publisher}'s backpressure
behavior.</dd>
<dt><b>Scheduler:</b></dt>
<dd>This version of {@code timeout} operates by default on the {@code computation} {@link Scheduler}.</dd>
</dl>

@param timeout
maximum duration between emitted items before a timeout occurs
@param timeUnit
the unit of time that applies to the {@code timeout} argument.
@return the source Publisher modified to notify Subscribers of a {@code TimeoutException} in case of a
timeout
@see <a href="http://reactivex.io/documentation/operators/timeout.html">ReactiveX operators documentation: Timeout</a>