static int shorten_default = 100;

sS shorten(CharSequence s) { ret shorten(s, shorten_default); }

sS shorten(CharSequence s, int max) {
  ret shorten(s, max, "...");
}

sS shorten(CharSequence s, int max, S shortener) {
  if (s == null) ret "";
  if (max < 0) ret str(s);
  return s.length() <= max ? str(s) : subCharSequence(s, 0, min(s.length(), max-l(shortener))) + shortener;
}

sS shorten(int max, CharSequence s) { ret shorten(s, max); }