static IntRange parseHexRange(S s) {
  LS parts = splitAtMinus(s);
  int start = hexToInt(first(parts));
  if (empty(parts))
    null;
  else if (l(parts) == 1)
    ret intRange_incl(start, start);
  else if (l(parts) == 2) {
    int end = hexToInt(second(parts));
    ret intRange_incl(start, end);
  } else
    fail("Too many minuses");
}