It doesn't matter in this example, but in terms of showing good ruby usage I think it's important that this has `|| super` tacked on the end to demonstrate the correct way to override `respond_to?`.  After all, instances of this class respond to `:inspect`, but this implementation of `respond_to?` will wrongly report that it doesn't respond to that message.

Actually, it would be even better to use `respond_to_missing?`.  That's a new method on 1.9 that allows `method` to work properly with these sorts of methods ([more info](http://robots.thoughtbot.com/post/28335346416/always-define-respond-to-missing-when-overriding))--which in turn allows the arity checking to work.  It's the good/correct way to make an object dynamically respond to messages on 1.9+, and I'd like the code we use here to lead readers to good ruby coding practices :).

If we do that, one issue is that `respond_to_missing?` doesn't work on 1.8.7.  However, given that the purpose of this file is documentation (and isn't really testing any new paths or behavior), we can just exclude this file from the 1.8.7 build, and not lose any confidence from having it excluded.