docs: public final static <T> Tuple2<Stream<T>, Stream<T>> duplicate(final Stream<T> stream) {
  
          final Tuple2<Iterator<T>, Iterator<T>> Tuple2 = Streams.toBufferingDuplicator(stream.iterator());
          return Tuple.tuple(
                            Streams.stream(Tuple2._1()), Streams.stream(Tuple2._2()));
      }