> A more useful signature would have been [returning the index]. Good point! And if you're doing that, there's no reason to use slices. So I guess the only thi

> A more useful signature would have been [returning the index]. Good point! And if you're doing that, there's no reason to use slices. So I guess the only thing to learn from my code... is that slices do useful bookkeeping for problems similar to this, in the case that you don't care about the indices? > Returning the value you were given or None would be better expressed as returning True/False to avoid the unnecessary copy. Just because two values are equal, doesn't mean they're the same. Though my function signature was wonky, regardless.