Hi,

Whatever be the level of the python programmer's expertise, I would strongly suggest he get a copy of Ovid's Beginning Perl. It was released in 2012, but it is still quite relevant. He might find the first few chapters "Meh", but chapter 6 onwards, the book starts getting into some real interesting stuff Perl offers. Chapter 7 (subroutines) is truly worth for someone who comes for another language, and that's just the beginning. The book is dense but if he goes through it, he'll learn enough to write amazing code, avoid pitfalls, be amazed by what Perl Testing has to offer and so on...