code: public static final <T> Transformer<T, T> orderedMergeWith(
              final Collection<Observable<T>> others, final Comparator<? super T> comparator) {
          return new Transformer<T, T>() {
  
              @Override
              public Observable<T> call(Observable<T> source) {
                  List<Observable<T>> collection = new ArrayList<Observable<T>>();
                  collection.add(source);
                  collection.addAll(others);
                  return OrderedMerge.<T> create(collection, comparator, false, RxRingBuffer.SIZE);
              }
          };
      }
docs: <p>
  Returns the source {@link Observable} merged with all of the other
  observables using the given {@link Comparator} for order. A precondition
  is that the source and other are already ordered. This transformer
  supports backpressure and its inputs must also support backpressure.
  
  <p>
  <img src=
  "https://github.com/davidmoten/rxjava-extras/blob/master/src/docs/orderedMerge.png?raw=true"
  alt="marble diagram">
  
  @param others
  a collection of already ordered observables to merge with
  @param comparator
  the ordering to use
  @param <T>
  the generic type of the objects being compared
  @return merged and ordered observable