svoid test_indexOfRangePredicate(int maxLength default 8) {
  for (S word : allWordsOfAlphabet_maxLength(maxLength, "ft")) {
    L<Bool> l = map(characters(word), c -> eq(c, "t"));
    assertEqualsVerbose(smartIndexOf(l, true),
      indexOfRangePredicate(l(l), (i, j) -> any(subList(l, i, j))));
  }
}