let x: Int? = 5

switch x {
case .some(let wrapped):
    print(wrapped) //Assosiated value bound to "wrapped"
case .none:
    print("nil")
}

func foo(_ arg: T) {
    switch arg {
    case array as Array<let X>:
        print("The argument is an array of (X)")
    default:
        print("The argument is not an array")
    }
}