I'm not crazy about this example, for a few reasons. IMO, it's nice when:

* the example is self-contained, so a user can just paste the code into lib/main.js and run it, and it has some visible output
* it's very clear what the example does
* the example has an absolute minimum of accidental complexity. This example needs people to understand promises and heritage.

However, I don't have a better example right now, and don't think that this ought to block landing the docs.