Some of the examples in the book violate the Zen of Python. So I wouldn't even call them pythonic or idiomatic in the first place. E.g.: `contains_zero` viola

Some of the examples in the book violate the Zen of Python. So I wouldn't even call them pythonic or idiomatic in the first place. E.g.: `contains_zero` violates "There should be one-- and preferably only one --obvious way to do it." `should_raise_shields` violate "Explicit is better than implicit." `linsolve` and `contains_duplicate` violate "Readability counts."