Yes, that was a super explanation from Václav. 
I ran it just to have a look and put the example in my “training” library.
It’s hard to tell who has coding experience and who is venturing into coding with Python, but…
Luc, you may recognize this as an example of namespace.
It seems possible that you’re fairly far along if you’re importing and linking modules that you wrote. Thanks for inspiring the lesson! Questions like this are what make discuss.python.org a great place to spend time!!
EDIT: I just ran across a topic on global vs. local namespace HERE. The scope of that discussion is functions within a single module but that topic is closely related to this one.