static Matches getFind3plusRests(S pat, S s) {
  L<S> tokpat = parse3_cachedPattern(pat), toks = parse3_cachedInput(s);
  Pair<S[], Int> p = find2plusIndex(tokpat, toks);
  if (p == null) null;
  new Matches m;
  m.m = concatStringArrays(
    new S[] {joinSubList(toks, 0, p.b-1)},
    p.a,
    new S[] {joinSubList(toks, p.b+l(tokpat)-1)});
  ret m;
}