python-message is a Python publish-subscribe broker for messages within an application. It allows components to subscribe to messages on topics and publish messages to subscribed listeners on those topics. Key features include using hashable objects like strings as topics, synchronous publishing to subscribed listeners, and APIs for subscribing, unsubscribing, publishing, and managing topic declarations. Examples show how it can decouple logging from libraries and allow dancing with processes, threads, and coroutines by decorating listener functions.