You don't get bonus points for hallucinating new problems, so why bother?

.lower() works in this case ???

ALWAYS

unless

...so?

Can you explain why such an alarmist statement?
Python default stack depth is 1000.
Here the program has a logarithmic complexity -
Meaning you will hit a RecursionError only if n > 2 ** 1000,
which is freaking huge!

Moreover recursion can be unavoidable in some cases:
Not all programs can be written as an iterative function,
and even more recursive programs require a stack -
which may be very tedious to maintain by hand.

lol, not really , sometimes a code does not have to pass for everything and that may end up defeating the purpose of the code

The description says you need to check for 'good' or 'bad' ideas. That's it. No capitalization, no upper case, no binary, no ASCII, nothing like that. That's the source of the downvotes. If you had to check for other ways good or bad might be written in, then the kata would be different and harder.

The statistics module doesn't accept non-positive (zero and negative numbers). It also performs operation on floats and doesn't guarantee exact results. See here.

Great, but don't forget using spoiler flag next time. Your post was visible in the homepage.

This doesn't happen in the tests, so I guess we don't have to support that.

Yes, that's right. Because this solution was written in Python 2. In Py2 filter() returned different thing. In this case, it returned a string.

It's not permutations, though the effect may seem very similar. It's only shifting. You just move 1st letter to the end of the string until you get the same string you started with. ..Yet nobody will explain anything to you in simple words here. Some advanced users, the one you've just addressed on top of them, made this forum a circle of mutual admiration and contempt to all with skills beneath theirs. This website stopped serving its purpose long ago.