input: Write a function to shuffle an array of integers using the random module. The function should return the shuffled array. If the input array is empty, the function should return an empty array.
  
  assert shuffle([1, 5, 9, 4, 2]) != [1, 5, 9, 4, 2]
  assert shuffle([1, 2, 3]) != [1, 2, 3]
  assert shuffle([]) == []
  assert shuffle([7]) == [7]
output: import random
  
  def shuffle(arr):
      if not arr:
          return []
      shuffled_arr = arr[:]
      random.shuffle(shuffled_arr)
      return shuffled_arr