[Dirty Equals] is a new python library by Samuel Colvin, the creator of Pydantic. It will transform how you write tests, especially for APIs. I made some contributions to it, which forever changed how I thought about `NotImplemented`. I thought it was a placeholder for unfinished work and unexpected use cases. I thought the language quirks it created in equality comparison were annoying. But in **DirtyEquals**, it’s a magic way to transform Python’s built in equality operator... And that changed how I think about language quirks, full stop.