static <A extends Concept> L<A> unlistedCopies(Class<A> c) {
  ret unlistedCopies(list(c));
}

static <A extends Concept> L<A> unlistedCopies(Collection<A> c) {
  new L<A> l;
  for (A a : c) {
    A b = unlisted((Class) a.getClass());
    ccopyFields(a, b);
    l.add(b);
  }
  ret l;
}