static CloseableShortIterator decodeOpusStream(S url) throws IOException {
  temp var res = tempResources();
  var in = res.add(httpInputStream(url));
  OpusMachine machine = res.add(new OpusMachine(in));

  //on clean exit { res.forget(); }
  ret with(-> res.forget(), new OpusMachineIterator(machine));
}