“I broke this rule because I developed some of the code while I was a Visiting Scientist at Google, so I followed the Google style guide, which deviates from PEP 8 in a few places. Once I got used to Google style, I found that I liked it. And at this point, it would be too much trouble to change.” Why would you write a book that targets the Python community and ignore PEP8 styling, inconveniencing an entire community…
"Many projects have their own coding style guidelines. In the event of any conflicts, such project-specific guides take precedence for that project."
and
"A Foolish Consistency is the Hobgoblin of Little Minds".
And, throughout, PEP8 makes it clear that it is a set of recommendations, and that if a project or community already has an established style, it need not be changed.