class Box {
  n: Int
}

class Holder {
  box: Box

  fn adopt(other: Box) {
    self.box = other
  }
}

fn keep(take b: Box) -> Int {
  return 0
}

fn leak(h: Holder) -> Box {
  return h.box
}

fn stash(h: Holder) -> Int {
  return keep(h.box)
}