verify() (answer: Bool) {
  original = vault.make("旧键")
  alias = original
  changed = vault.change(original, "新键")
  alias.label = "别名"
  answer = vault.read(original) == "旧键" and vault.read(alias) == "旧键" and vault.read(changed) == "新键" and original.label == "原名" and alias.label == "别名" and changed.label == "原名"
}