Python Best Practices

This is a comprehensive Python style guide distilled from real PR review patterns, covering 70 rules across data modeling, error handling, type safety, and API design. It assumes Python 3.11+ and includes impact ratings so you know what matters (like fixing mutable defaults and catching specific exceptions) versus what's just preference (like naming conventions). The rules are pragmatic about when to apply them: new code gets the full treatment, but stable code shouldn't be churned for style points. Worth having on hand if you're doing code reviews or want to stop debating the same patterns repeatedly. The discriminated unions and timezone-aware datetime guidance alone will save you from common footguns.