You can&#x27;t write code that is guaranteed to work on Python 4, but you definitively can write code that is guaranteed that <i>will not</i> work on Python 4.<p>That&#x27;s what this article is about, anyway. Based on the issues with Py3 I&#x27;m quite confident that switch from 3 to 4 will be similar as from 1 to 2.