I hadn't read the description till the end. Not my first time 🙄

i added more personalized assertion messages to Python

or perhaps just a reminder from the description:

cheater u can't use restricted characters!

The error message is confusing:

cheater u can't use digits !!!: True should equal False

Maybe or math operators should be added.

You used + in your code.

Good point.

the Chars type that chars() returns implements the Iterator trait. So you should be able to filter right off chars().