src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> takeLast(int count) {
        if (count < 0) {
            throw new IndexOutOfBoundsException("count >= 0 required but it was " + count);
        } else
        if (count == 0) {
            return RxJavaPlugins.onAssembly(new ObservableIgnoreElements<T>(this));
        } else
        if (count == 1) {
            return RxJavaPlugins.onAssembly(new ObservableTakeLastOne<T>(this));
        }
        return RxJavaPlugins.onAssembly(new ObservableTakeLast<T>(this, count));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> takeLast(int count) {
        if (count < 0) {
            throw new IndexOutOfBoundsException("count >= 0 required but it was " + count);
        } else
        if (count == 0) {
            return RxJavaPlugins.onAssembly(new ObservableIgnoreElements<T>(this));
        } else
        if (count == 1) {
            return RxJavaPlugins.onAssembly(new ObservableTakeLastOne<T>(this));
        }
        return RxJavaPlugins.onAssembly(new ObservableTakeLast<T>(this, count));
    }
Returns an Observable that emits at most the last {@code count} items emitted by the source ObservableSource. If the source emits fewer than
{@code count} items then all of its items are emitted.
<p>
<img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/takeLast.n.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>This version of {@code takeLast} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param count
the maximum number of items to emit from the end of the sequence of items emitted by the source
ObservableSource
@return an Observable that emits at most the last {@code count} items emitted by the source ObservableSource
@throws IndexOutOfBoundsException
if {@code count} is less than zero
@see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>