input: Write a function to shuffle an array of integers and return the shuffled array.
  assert shuffle([1, 5, 9, 4, 2]) == [5, 2, 4, 9, 1] or shuffle([1, 5, 9, 4, 2]) == [4, 9, 1, 2, 5] or shuffle([1, 5, 9, 4, 2]) == [9, 4, 1, 5, 2] or shuffle([1, 5, 9, 4, 2]) == [2, 1, 5, 9, 4] or shuffle([1, 5, 9, 4, 2]) == [1, 4, 5, 2, 9]
output: import random
  
  def shuffle(arr):
      random.shuffle(arr)
      return arr