sclass OrderedMultiIterator<A extends Comparable<A>> {
  srecord noeq Stream<A>(Iterator<A> iterator, A element) is Comparable<Stream<A>> {
    public int compareTo(Stream<A> stream) {
      ret element.compareTo(stream.element);
    }
  }
  
  new TreeSet<Stream> streams;
  
  void add(Iterator<A> iterator) {
    if (iterator == null || !iterator.hasNext()) ret;
    A element = iterator.next();
    streams.add(new Stream<A>(iterator, element));
  }
  
  void addAll(Iterable<? extends Iterator<A>> iterators) {
    fOr (it : iterators) add(it);
  }
}