It's not hard, with some modest experience (say 1-2 years of professional work or serious amateur interest), to extrapolate from his deliberately high-level discussion (it was written for a blog/newsletter, not for a book) to something more interesting and "real world". What's hard is coming up with an example that's nearly complete and fits into something the size of a newsletter or comment. He did an alright job of it, just left the readers with the need to exercise their gray matter a bit.

If it is not hard, with an experience of this guy, he could came up with a better example? It is your own words so I am sure you will agree? He did alright job so he could exercise gray matter a bit and came up with some API for saving customer data and then test it his way? I mean... This would be more interesting and "real world" so I am sure it would be worth to write longer blog post about it!