[pjmlp]

Well, import ctypes.

Are you sure you master all language and library changes between versions, even minor ones?

What are the major differences between Python 1.5 and Python 3.10?

[nicoburns]

Why does it matter how Python 1 worked? Nobody is using that these days. In fact , in 2022 you can probably even get away without knowing python 2 either.

[pjmlp]

Until you find libraries that were never updated....

Very lucky ones, those that can do their work from scratch using latest version of everything, including the OSes where they get deployed.