input: Write a function to shuffle an array.
  assert len(shuffle_array([1, 2, 3, 4, 5])) == 5
  assert sorted(shuffle_array([1, 2, 3, 4, 5])) == [1, 2, 3, 4, 5]
  assert len(shuffle_array([10, 20, 30, 40, 50])) == 5
output: import random
  
  def shuffle_array(arr):
      random.shuffle(arr)
      return arr