input: def swap(arr1, arr2):
      """
      Swap the elements of the two given arrays.
      >>> swap([3, 5, 6, 9], [2, 4, 7, 8])
      ([2, 4, 7, 8], [3, 5, 6, 9])
      """
      assert len(arr1) == len(arr2)
      for i in range(len(arr1)):
          temp = arr1[i]
          arr1[i] = arr2[i]
          arr2[i] = temp
      return arr1, arr2
output:     assert len(arr1) == len(arr2)
      for i in range(len(arr1)):
          temp = arr1[i]
          arr1[i] = arr2[i]
          arr2[i] = temp
      return arr1, arr2