Good references are vital for good work and I see every sign that this is such a book.
This book is a plain reference book and nothing more. Whether it is essential is a matter for the individual to decide. The so-called tutorial of chapter 1 is just a quick reminder of the basics of the language; what more would you expect in ten pages. The rest of the first quarter of the book covers the core language. I did not notice any serious errors but it is very hard (even for a real expert with a language, which I am not for Python) to authenticate everything in a reference book.
The index consumes the last forty-five pages. A large index is no bad thing in a reference book. Just before the index you will find twenty-six pages covering extending and embedding Python.
The rest, about half the book, covers the built-in functions and the libraries.
I suspect that this book will become as well thumbed, when I get time to write some Python, as my fast disintegrating copy of the C- Standard, P.J. Plauger's reference books on C and my copy of The C++ Programming Language 3rd ed . Good references are vital for good work and I see every sign that this is such a book.