input: Write a function to sort a list of numbers in descending order.
  assert sortDescending([1, 12, 3, 8]) == [12, 8, 3, 1]
  assert sortDescending([10, 5, 3, 20]) == [20, 10, 5, 3]
  assert sortDescending([4, 2, 9, 7]) == [9, 7, 4, 2]
output: def sortDescending(numbers):
      return sorted(numbers, reverse=True)