input: Write a function to shuffle elements of a list using the Fisher-Yates algorithm.
  assert randomize([1, 2, 3, 4, 5], 5) != [1, 2, 3, 4, 5]
  assert len(randomize([1, 2, 3, 4, 5], 5)) == 5
  assert sorted(randomize([10, 20, 30, 40], 4)) == [10, 20, 30, 40]
output: import random
  
  def randomize(lst, n):
      for i in range(n - 1, 0, -1):
          j = random.randint(0, i)
          lst[i], lst[j] = lst[j], lst[i]
      return lst