这些字典查询会依次输出哪三种状态？

let scores: [String: Int?] = ["ready": 8, "waiting": nil]

func state(_ value: Int??) -> String {
    switch value {
    case .none: return "missing"
    case .some(.none): return "waiting"
    case .some(.some(let score)): return "score=\(score)"
    }
}

print(state(scores["ready"]))
print(state(scores["waiting"]))
print(state(scores["unknown"]))