hop of those help? Well, it depends. Usually, constants are defined at module level. But if you have many constants for category_a and category_b, it might even make sense to add a subpackage constants with modules constants.category_a and constants.category_b. I would refrain from using a class - it could be instanciated, which wouldn't make sense, and it has no advantage over a module apart from allowing you to cram more than one into one physical file (which you propably shouldn't if there are so many constants). The Java version would propably use a static class, but the Python equivalent is a module.
Python PIL Image Module ImportError: No module named PIL, No module named Image