While it is fairly trivial in Python to import a "child" module into another module and list its attributes, it becomes slightly more difficult when you want to import all child modules.
I'm building a library of tools for an existing 3D application.  Each tool has its own menu item and sub menus. I'd like the tool to be responsible for creating its own menus as many of them change based on context and templates.  I'd like my base module to be able to find all child modules and check for a create_menu() function and call it if it finds it.
What is the easiest way to discover all child modules?
The solution above traversing the filesystem for finding submodules is ok as long as you implement every plugin as a filesystem based module.
A more flexible way would be an explicit plugin list in your main module, and have every plugin (whether a module created by file, dynamically, or even instance of a class) adding itself to that list explicitly. Maybe via a registerPlugin function.
Remember: "explicit is better than implicit" is part of the zen of python.
How to find all child modules in Python?