input: Write a function to swap two random elements in a list using the random module.
  assert swap_random_elements([1, 2, 3, 4, 5])!=[1, 2, 3, 4, 5]
  assert len(swap_random_elements([10, 20, 30, 40, 50]))==5
  assert set(swap_random_elements([5, 6, 7, 8, 9]))=={5, 6, 7, 8, 9}
output: import random
  
  def swap_random_elements(lst):
      if len(lst) < 2:
          return lst
      idx1, idx2 = random.sample(range(len(lst)), 2)
      lst[idx1], lst[idx2] = lst[idx2], lst[idx1]
      return lst