I almost have for the function descnedant. Could some one please help? Here is my code.

import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    func descendant(_ first: Int, _ rest: Int) -> Any? {
        print("\(first) \(rest)")
        return descendant(_:_:)
    }
    descendant(4, 9)

}

}

Not really sure what it is you're trying to do here. Can you clarify?

What I'm trying to do is print out the numbers of the descendants.

I think I found the soultion.

import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    func descendant(_ first: Int, _ rest: Int) -> Any? {
        print("\(first) \(rest)")
        return descendant(_:_:)
    }
    print(descendant(4, 9)!)

}

}

The output that I see is: 4 9 (Function) could anyone tell me if this would be correct?

If all you want to do is print out the numbers, then this will work:

override func viewDidLoad() {
    super.viewDidLoad()

    func descendant(_ first: Int, _ rest: Int) {
        print("\(first) \(rest)")
    }
    descendant(4, 9)

}

You don't need to return anything from descendant since you handle the printing inside that function.

Thank you for your help. It worked like a charm.