static S formatXYZ_appendRest(S pattern, L<S> args) {
  L<S> tok = javaTokC(pattern);
  L<S> restArgs = cloneList(args);
  for (int idx : (L<Int>) reverseSorted(map(f formatXYZ_varToIndex_maybeQuoted, tok)))
    remove(restArgs, idx-1);
  ret join(" ", concatLists(
    ll(formatXYZ(pattern, args)),
    restArgs));
}