static <A> S stringTrie_longestPrefix_loose(StringTrie<A> trie, S string) {
  int n = 0;
  S s = string;
  while licensed {
    if (trie == null) break;
    if (empty(string)) break;
    S prefix = trie.longestLocalPrefix(s);
    if (empty(prefix)) break;
    n += l(prefix);
    trie = trie.getChild(prefix);
    s = dropFirst(s, l(prefix));
  }
  ret takeFirst(n, string);
}

Began life as a copy of #1030182