svoid test_UniquifyUsingHasher() {
  UniquifyUsingHasher<S, Int> u = new(s -> l(s));
  int n = 1000, maxL = 10;
  LS l = repF(-> randomOverAlphabet("ab", random(maxL)));
  LS expected = uniquify(l);
  LS actual = u.addAll(l)!;
  print(n + " => " + l(expected));
  assertListsEqual(expected, actual);
}