input: Write a function to take two arrays of integers as input and swap their elements. The function should ensure that the arrays are of the same length before performing the swap.
  
  def swap(arr1, arr2):
      assert len(arr1) == len(arr2)
      for i in range(len(arr1)):
          temp = arr1[i]
          arr1[i] = arr2[i]
          arr2[i] = temp
  
  assert swap([3, 5, 6, 9], [2, 4, 7, 8]) == ([2, 4, 7, 8], [3, 5, 6, 9])
  assert swap([1, 2, 3, 4], [5, 6, 7, 8]) == ([5, 6, 7, 8], [1, 2, 3, 4])
  assert swap([], []) == ([], [])
output: def swap(arr1, arr2):
      if len(arr1) == len(arr2):
          for i in range(len(arr1)):
              arr1[i], arr2[i] = arr2[i], arr1[i]