input: Write a python function to shuffle elements in a list.
  assert len(shuffle_list([1, 2, 3, 4, 5])) == 5
  assert set(shuffle_list([1, 2, 3, 4, 5])) == {1, 2, 3, 4, 5}
  assert shuffle_list([1]) == [1]
output: def shuffle_list(lst):
      import random
      random.shuffle(lst)
      return lst