在python模块docstring中放置什么?

Ok, so I've read both PEP 8 and PEP 257, and I've written lots of docstrings for functions and classes, but I'm a little unsure about what should go in a module docstring. I figured, at a minimum, it should document the functions and classes that the module exports, but I've also seen a few modules that list author names, copyright information, etc. Does anyone have an example of how a good python docstring should be structured?, and I'