Ask HN: What are some unusual but useful Python libraries you've discovered?

Hey everyone! I'm always on the lookout for new and interesting Python libraries that might not be well-known but are incredibly useful. Recently, I stumbled upon Rich for beautiful console output and Pydantic for data validation, which have been game-changers for my projects. What are some of the lesser-known libraries you've discovered that you think more people should know about? Share your favorites and how you use them!