static ItIt<T3<S>> ai_findInfixPhrases(S s, Collection<S> phrases) {
  final Set<S> set = asCISet(phrases);
  L<S> tok = javaTokNPunctuation(s);
  ret notNulls_iterator(
    // first, split on the left
    nestedIterator(allTokSplits_nOnRight_iterator(tok),
      func(final Pair<LS> p) -> ItIt<T3<S>> {
        // now split the right part
        L<S> tok2 = javaTokNPunctuation(p.b);
        ret mapI(allTokSplits_nOnLeft_iterator(tok2),
          func(Pair<LS> p2) -> T3<S> {
            set.contains(trimJoin(simpleSpaces(p2.a)))
              ? t3(join(p.a), join(p2.a), join(p2.b)) : null
          });
      }));
}