static L<S> ai_autoComplete(fS s, int maxEntries, int timeout) {
  ret (S) evalWithTimeoutOrNull(func { ai_autoComplete_impl(s, maxEntries) }, timeout);
}

static L<S> ai_autoComplete_impl(S s, maxEntries) {
  ret takeFirst(maxEntries, fullIndexedTermsStartingWith(s));
}