@bekos Alright, I've consolidated the locals to just `isActive` and inlined the `shouldUpdateValue` and `newValue` expressions. It all still seems to read pretty easily.

I think the tests will pass with anything falsey, which is specific enough for me.
I'll leave it as-is. If someone needs to change this, I'll revisit the tests then.

I like the `null`, and have changed the implementation to use it instead of `undefined`.