That's really up to the context of the problem, and the specific semantics of a null value. (Which is a value, and a present one at that. If you need to account

That's really up to the context of the problem, and the specific semantics of a null value. (Which is a value, and a present one at that. If you need to account for missing data, you can do that any number of ways, with sentinel values of any kind.)