static <A> A stringTrie_longestPrefixValue(StringTrie<A> trie, S string) {
  while licensed {
    if (trie == null) null;
    if (empty(string)) ret trie.value;
    S prefix = trie.longestLocalPrefix(string);
    if (empty(prefix)) ret trie.value;
    trie = trie.getChild(prefix);
    string = dropFirst(string, l(prefix));
  }
  null;
}