src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> doAfterNext(Consumer<? super T> onAfterNext) {
        ObjectHelper.requireNonNull(onAfterNext, "onAfterNext is null");
        return RxJavaPlugins.onAssembly(new ObservableDoAfterNext<T>(this, onAfterNext));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> doAfterNext(Consumer<? super T> onAfterNext) {
        ObjectHelper.requireNonNull(onAfterNext, "onAfterNext is null");
        return RxJavaPlugins.onAssembly(new ObservableDoAfterNext<T>(this, onAfterNext));
    }
Calls the specified consumer with the current item after this item has been emitted to the downstream.
<p>Note that the {@code onAfterNext} action is shared between subscriptions and as such
should be thread-safe.
<p>
<img width="640" height="360" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/doAfterNext.o.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code doAfterNext} does not operate by default on a particular {@link Scheduler}.</dd>
<dt><b>Operator-fusion:</b></dt>
<dd>This operator supports boundary-limited synchronous or asynchronous queue-fusion.</dd>
</dl>
<p>History: 2.0.1 - experimental
@param onAfterNext the Consumer that will be called after emitting an item from upstream to the downstream
@return the new Observable instance
@since 2.1