input: Write a function to sort a list of integers in descending order. If the list is empty, it should return the empty list. Otherwise, it should return the sorted list.
  assert sort_descending([3, 7, 5, 8, 10])==[10, 8, 7, 5, 3]
  assert sort_descending([])==[]
  assert sort_descending([1, 2, 3, 4, 5])==[5, 4, 3, 2, 1]
  assert sort_descending([100, 1, 1000, 10])==[1000, 100, 10, 1]
  assert sort_descending([9, 9, 9, 9])==[9, 9, 9, 9]
output: def sort_descending(lst):
      return sorted(lst, reverse=True)