Could provide a example on python of non-intentional bad code, like the kind that could be write by a perl coder, that make them not understand it a week later?

Could provide a example on python of non-intentional bad code, like the kind that could be write by a perl coder, that make them not understand it a week later? Because that is the issue I was talking about is rare in python. Is true that is possible to write bad in any language, but certainly is harder in some of them