input: Write a function to shuffle an array of integers using the built-in shuffle function from the random module. The function should accept an array as input and return the shuffled array. If the array is empty, it should return an empty array.
  def shuffle(arr):
      if not arr:
          return []
      random.shuffle(arr)
      return arr
  
  assert shuffle([1, 5, 9, 4, 2])!=None
  assert shuffle([])==[]
output: def shuffle(arr):
      if not arr:
          return []
      random.shuffle(arr)
      return arr