The most impressive part of the talk was when Armin demonstrated the “online” debugging feature on a standard error page generated by Werkzeug. Upon each error the context in which it happens is stored on the server (only if the app is in the debug mode). Thus on the error page itself you can directly interact with the Python interpreter which is “frozen” in the very state in which the error happened. So you can use the full power of the interactive Python interpreter directly on the standard error page. That’s awesome.