This `return` is so that the method bails early and doesn't memoize a result, right?

Also, `if_required_and_missing` is a required parameter. We don't need to check that it was passed, yeah? If people pass in explicit `nil` where a block should be, they fail (and the tests will surely catch it). This isn't part of the public interface of the gem, so it's really just us we have to worry about.

Given those two facts, I think the inside of this block can just be:

```ruby
if_required_and_missing.call && nil
```