src/main/java/io/reactivex/Flowable.java
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Flowable<T> takeLast(long count, long time, TimeUnit unit) {
        return takeLast(count, time, unit, Schedulers.computation(), false, bufferSize());
    }
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Flowable<T> takeLast(long count, long time, TimeUnit unit) {
        return takeLast(count, time, unit, Schedulers.computation(), false, bufferSize());
    }
Returns a Flowable that emits at most a specified number of items from the source Publisher that were
emitted in a specified window of time before the Publisher completed.
<p>
<img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/takeLast.tn.png" alt="">
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The operator honors backpressure from downstream and consumes the source {@code Publisher} in an
unbounded manner (i.e., no backpressure is applied to it).</dd>
<dt><b>Scheduler:</b></dt>
<dd>{@code takeLast} does not operate on any particular scheduler but uses the current time
from the {@code computation} {@link Scheduler}.</dd>
</dl>

@param count
the maximum number of items to emit
@param time
the length of the time window
@param unit
the time unit of {@code time}
@return a Flowable that emits at most {@code count} items from the source Publisher that were emitted
in a specified window of time before the Publisher completed
@see <a href="http://reactivex.io/documentation/operators/takelast.html">ReactiveX operators documentation: TakeLast</a>