Classes must be nouns but not every noun must be a class. If your class only has two methods and one of them is init you probably meant to write a function.
MuffinMail recently refactored their API; it went from 20 classes scattered in 22 modules down to 1 class just 15 lines long. It was a welcome change, but we'll further refactor that down to a single function 3 lines long.
The Python stdlib is an example of a namespace that is relatively flat. You won't find packages that consist of a single module defining an exception, and you won't find many exceptions at all - just 165 kinds in 200k lines of code. That's a tiny ratio compared to most projects including Django.
Of course there are things, like containers, that should be classes. As a final example we'll add a Heap type to the heapq module (admit it, you already have one in your utils.py).