Improve Code Quality of python lib

[ByteOtter]

What would you like to be added:

#270 switched the previously introduced lining tools to mypy amongst other things. Currently, there are numerous problems in the style checking CI that would need adressing.

Why is this needed:

This would help keeping the code clean and in compliance with python best practices.

[ByteOtter]

Given the imminent changes of #270, this needs to reworded and picked up later again.