static <A> Map<A, L<A>> listToMapOfListsWithKeyDetector(IPred<A> keyDetector, L<A> l, A preludeKey) {
  new LinkedHashMap<A, L<A>> map;
  L<A> currentList = null;
  fOr (A a : l)
    if (keyDetector.get(a))
      map.put(a, currentList = new L);
    else {
      if (currentList == null)
        map.put(preludeKey, currentList = new L);
      currentList.add(a);
    }
  ret map;
}