src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<Timed<T>> timeInterval() {
        return timeInterval(TimeUnit.MILLISECONDS, Schedulers.computation());
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<Timed<T>> timeInterval() {
        return timeInterval(TimeUnit.MILLISECONDS, Schedulers.computation());
    }
Returns an Observable that emits records of the time interval between consecutive items emitted by the
source ObservableSource.
<p>
<img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/timeInterval.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code timeInterval} does not operate on any particular scheduler but uses the current time
from the {@code computation} {@link Scheduler}.</dd>
</dl>

@return an Observable that emits time interval information items
@see <a href="http://reactivex.io/documentation/operators/timeinterval.html">ReactiveX operators documentation: TimeInterval</a>