src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U, R> Observable<R> zipWith(Iterable<U> other,  BiFunction<? super T, ? super U, ? extends R> zipper) {
        ObjectHelper.requireNonNull(other, "other is null");
        ObjectHelper.requireNonNull(zipper, "zipper is null");
        return RxJavaPlugins.onAssembly(new ObservableZipIterable<T, U, R>(this, other, zipper));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final <U, R> Observable<R> zipWith(Iterable<U> other,  BiFunction<? super T, ? super U, ? extends R> zipper) {
        ObjectHelper.requireNonNull(other, "other is null");
        ObjectHelper.requireNonNull(zipper, "zipper is null");
        return RxJavaPlugins.onAssembly(new ObservableZipIterable<T, U, R>(this, other, zipper));
    }
Returns an Observable that emits items that are the result of applying a specified function to pairs of
values, one each from the source ObservableSource and a specified Iterable sequence.
<p>
<img width="640" height="380" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/zip.i.png" alt="">
<p>
Note that the {@code other} Iterable is evaluated as items are observed from the source ObservableSource; it is
not pre-consumed. This allows you to zip infinite streams on either side.
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code zipWith} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param <U>
the type of items in the {@code other} Iterable
@param <R>
the type of items emitted by the resulting ObservableSource
@param other
the Iterable sequence
@param zipper
a function that combines the pairs of items from the ObservableSource and the Iterable to generate
the items to be emitted by the resulting ObservableSource
@return an Observable that pairs up values from the source ObservableSource and the {@code other} Iterable
sequence and emits the results of {@code zipFunction} applied to these pairs
@see <a href="http://reactivex.io/documentation/operators/zip.html">ReactiveX operators documentation: Zip</a>