static boolean find3plusRestsX(S pat, S s) {
  return find3plusRestsX(pat, s, null);
}

static boolean find3plusRestsX(S pat, S s, Matches matches) {
  pat = dropPrefix("...", dropSuffix("...", pat));
  L<S> tokpat = parse3(pat), toks = parse3(s);
  Pair<S[], Int> p = find2plusIndex(tokpat, toks);
  //print(structure(tokpat) + " on " + structure(toks) + " => " + structure(m));
  if (p == null) false;
  if (matches != null)
    matches.m = concatStringArrays(
      new S[] {joinSubList(toks, 0, p.b-1)},
      p.a,
      new S[] {joinSubList(toks, p.b+l(tokpat)-1)});
  true;
}

Began life as a copy of #1014422