extension KeyedDecodingContainer {
    func decode<T>(_ key: K, default: T) throws -> T where T: Codable {
        return try self.decodeIfPresent(T.self, forKey: key) ?? `default`
    }

    func decode<T>(_ key: K) throws -> T where T: Codable {
        return try self.decode(T.self, forKey: key)
    }
}

// Example
let values = try decoder.container(keyedBy: CodingKeys.self)
optionalName = try values.decode(.optionalName, default: "N/A")
requiredName = try values.decode(.requiredName)