import Foundation

func countUpAndDown(for number: Int) {
    print("Going up!")
    for i in 0..<number {
        print(i)
    }
    
    print("At the top!\nGoing down...")
    
    for i in (0..<number).reversed() {
        print(i)
    }
  
    print("Back down. Bye!")
}

public func countUpAndDownDriver() {
    countUpAndDown(for: 10)
}
