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