input: Write a function to sort a list of items in descending order using Python. If the input list is empty, return the empty list. The function should modify the original list and return None.
  assert sort_descending([3, 7, 5, 8, 10]) == None
  assert sort_descending([]) == None
  list_items = [3, 7, 5, 8, 10]
  sort_descending(list_items)
  assert list_items == [10, 8, 7, 5, 3]
  list_items = []
  sort_descending(list_items)
  assert list_items == []
output: def sort_descending(items):
      items.sort(reverse=True)