new dupe in {
  contract dupe(@depth) = {
    if (depth <= 0) {
      Nil
    } else {
      dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1) | dupe!(depth - 1)
    }
  } | dupe!(2)
}