This whole debate makes newcomers to run away, it's confusing, nonsense and more importantly a bubble, fairy dust, it doesn't exist and it shouldn't be there, It's only the Python and that's it.
If you're on the older version (Python 2 as you say), you're a decade behind, you should have upgraded at 2008.
You wanna say
2to3, or tiny stuff that are deprecated? If you forget to upgrade you hit those too, no surprise.