src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> skipLast(int count) {
        if (count < 0) {
            throw new IndexOutOfBoundsException("count >= 0 required but it was " + count);
        }
        if (count == 0) {
            return RxJavaPlugins.onAssembly(this);
        }
        return RxJavaPlugins.onAssembly(new ObservableSkipLast<T>(this, count));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> skipLast(int count) {
        if (count < 0) {
            throw new IndexOutOfBoundsException("count >= 0 required but it was " + count);
        }
        if (count == 0) {
            return RxJavaPlugins.onAssembly(this);
        }
        return RxJavaPlugins.onAssembly(new ObservableSkipLast<T>(this, count));
    }
Returns an Observable that drops a specified number of items from the end of the sequence emitted by the
source ObservableSource.
<p>
<img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/skipLast.png" alt="">
<p>
This Observer accumulates a queue long enough to store the first {@code count} items. As more items are
received, items are taken from the front of the queue and emitted by the returned ObservableSource. This causes
such items to be delayed.
<dl>
<dt><b>Scheduler:</b></dt>
<dd>This version of {@code skipLast} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param count
number of items to drop from the end of the source sequence
@return an Observable that emits the items emitted by the source ObservableSource except for the dropped ones
at the end
@throws IndexOutOfBoundsException
if {@code count} is less than zero
@see <a href="http://reactivex.io/documentation/operators/skiplast.html">ReactiveX operators documentation: SkipLast</a>