What's an example of a 'simple python question that someone failed?' And was it something that truly showed incompetance? In my experience, it turns out to be

What's an example of a 'simple python question that someone failed?' And was it something that truly showed incompetance? In my experience, it turns out to be some dark corner of the language, or a keyword that's not in common use today. Examples are: 'void' in JavaScript and 'boxing' in C#