Mark all symbols not supposed to be exposed as private

[spbnick]

Figure out the correct way for, and mark all symbols not explicitly supposed to be exposed as private to avoid unintended use and unnecessary coupling.

Check Python conventions, and available technical solutions, to mark module-public symbols which are library-private. I.e. symbols which are used by other modules in the library, but are not supposed to be used outside the library.

[mrbazzan]

@spbnick I'm interested in this issue. Do I need additional information?

[spbnick]

@mrbazzan, yeaah, this one is not so straightforward, as you would need to figure out which symbols are useful to library users and which are not. However, you can help a lot if you do the research on the ways to implement that.