这段程序会输出什么？

final class Token {
    let id: String

    init(id: String) {
        self.id = id
        print("created", id)
    }

    deinit {
        print("released", id)
    }
}

var primary: Token? = Token(id: "T1")
var backup = primary
primary = nil
print(backup?.id ?? "none")
backup = nil