You don't need to use `None`. If you indeed aren't planning to mutate the argument, then use something immutable that provides the necessary interface. Typically, this will be `()`, and then your logic doesn't require the special case. I genuinely don't understand, after 20+ years of this, why everyone else has decided that the `None` check should be idiomatic. It's just, ugh. I'm pretty sure I've even seen people do this where a string is expected and `''` is right there staring at them as the obvious option.