input: Write a function to swap the elements of two arrays of integers of the same length. The function should take two arrays as input and assert that they are of the same length. If they are, it should swap their elements.
  assert swap([3, 5, 6, 9], [2, 4, 7, 8])==None
  assert swap([], [])==None
  assert swap([1, 2, 3], [4, 5, 6])==None
output: def swap(arr1, arr2):
      assert len(arr1) == len(arr2)
      for i in range(len(arr1)):
          arr1[i], arr2[i] = arr2[i], arr1[i]