∀ {state : Std.Mutex Std.CancellationContext.State} {token : Std.CancellationToken} {id : UInt64}
  {state_1 : Std.Mutex Std.CancellationContext.State} {token_1 : Std.CancellationToken} {id_1 : UInt64},
  { state := state, token := token, id := id } = { state := state_1, token := token_1, id := id_1 } →
    state = state_1 ∧ token = token_1 ∧ id = id_1