input: Write a function to take as input two arrays of integers and swap their elements. If the length of the two arrays is not equal, raise an AssertionError.
  assert swap([3, 5, 6, 9], [2, 4, 7, 8]) == None
  assert swap([1, 2, 3], [4, 5, 6]) == None
output: def swap(arr1, arr2):
      assert len(arr1) == len(arr2), "Arrays must be of equal length"
      arr1[:], arr2[:] = arr2[:], arr1[:]