input: Write a function to sort a list in descending order. If the list is empty, the function should return the empty list without any modification.
  
  assert sort_descending([3, 7, 5, 8, 10])==[10, 8, 7, 5, 3]
  assert sort_descending([1, 2, 3, 4, 5])==[5, 4, 3, 2, 1]
  assert sort_descending([])==[]
  assert sort_descending([9, 2, 6, 8, 3])==[9, 8, 6, 3, 2]
  assert sort_descending([7])==[7]
output: def sort_descending(lst):
      return sorted(lst, reverse=True)