In a previous post I had mentioned I co-authored a book on IOS XE Programmability with some colleagues of mine. For those who are interested, the book is available here.
The book is not a comprehensive how-to, but a summary of the IOS XE features along with a few samples. It should provide a good overview of the capabilities of IOS XE. For those who were on my CCIE webinar, it should be more than adequate to get you up to speed on CCIE written programmability topics.
As with any technical book, there could be some errata, so please feel free to pass them along and I can get them corrected in the next edition.