input: def count_down_while(num: int) -> None:
      """ Takes a positive integer and uses a while loop to output numbers counting down to 1.
      >>> count_down_while(6)
      6
      5
      4
      3
      2
      1
      Done!
      >>> count_down_while(3)
      3
      2
      1
      Done!
      """
output:     while num > 0:
          print(num)
          num -= 1
      print("Done!")