enum NESWDirection {
  north(0, -1),
  east(1, 0),
  south(0, 1),
  west(-1, 0);
  
  // cache values()
  static final selfType values[] = values();
  
  private final gettable int x;
  private final gettable int y;
  
  *(int *x, int *y) {}
  
  int index() { ret ordinal(); }
  
  NESWDirection plus(int i) {
    ret getNESWDirection(index()+i);
  }
}