input: Write a function to sort 3 randomly selected numbers from a list in descending order.
  assert sort_numbers([4, 7, 9, 11, 33, 2])!=[]
  assert sort_numbers([10, 20, 30, 40, 50, 60, 70])!=[]
  assert sort_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])!=[]
output: import random
  
  def sort_numbers(lst):
      selected_numbers = random.sample(lst, 3)
      selected_numbers.sort(reverse=True)
      return selected_numbers