Comments should explain the "why" and not the "what". The code _should_ explain the what just fine, but it doesn't explain the problem the code is trying to so

Comments should explain the "why" and not the "what". The code _should_ explain the what just fine, but it doesn't explain the problem the code is trying to solve at all. If you struggle to explain the why with a docstring or few comments, then that's a sign you didn't decompose the problem enough.