input: Write a function to shuffle an array of integers. The function should use the `random.shuffle` method to rearrange the elements of the array randomly.
  assert shuffle([1, 5, 9, 4, 2])==[5, 1, 4, 9, 2] # Example output, actual output will vary due to randomness
  assert shuffle([2, 7, 8, 3, 6, 9])==[3, 9, 6, 2, 7, 8] # Example output, actual output will vary due to randomness
  assert shuffle([10, 20, 30])==[20, 10, 30] # Example output, actual output will vary due to randomness
  assert shuffle([])==[] # Edge case for empty array
output: def shuffle(arr):
      import random
      random.shuffle(arr)
      return arr