struct User {
  let firstName: String
  let lastName: String?
}

extension User: Codable {
}


struct Generic<Value> {
  var value: Value
}

extension Generic {
}

extension Generic: Codable where Value: Codable {
}


struct Outer {
  struct Inner {
    let value: Int
  }
}

extension Outer.Inner: Codable {

    private enum CodingKeys: CodingKey {
      case value
    }

    init(from decoder: any Decoder) throws {
      let container: KeyedDecodingContainer<Outer.Inner.CodingKeys> = try decoder.container(keyedBy: Outer.Inner.CodingKeys.self)

      self.value = try container.decode(Int.self, forKey: Outer.Inner.CodingKeys.value)

    }

    func encode(to encoder: any Encoder) throws {
      var container = encoder.container(keyedBy: Outer.Inner.CodingKeys.self)

      try container.encode(self.value, forKey: Outer.Inner.CodingKeys.value)
    }
}