Esri Press has a book for all those Python people looking to develop their scripting skills. And, if you purchase through the UC20 Merch Store, you get a pretty cool discount.
Hi Joe - the book is technically in pre-publication status. The merch store had it for sale as a UC perk. You are welcome to pre-order from a book retailer like Amazon or Barnes and Noble.
Here is a link to more info: https://esripress.esri.com/display/index.cfm?fuseaction=display&websiteID=393&moduleID=1