sclass OpusMachineIterator extends CloseableShortIterator {
  OpusMachine machine;
  *(OpusMachine *machine) { ownResource(machine); }
  
  !include #1033023 // Resources mix-in
  
  int val = Int.MAX_VALUE;
  
  bool hasNext() {
    if (val == Int.MAX_VALUE)
      val = machine!;
    ret val != Int.MIN_VALUE;
  }
      
  short next() {
    if (!hasNext()) fail("No such element");
    var v = val;
    val = Int.MAX_VALUE;
    ret (short) v;
  }
}