Dear list, as I am already quite experienced in python programming I recently started to dive into the C-depths of the language. So it was a logical implication to register for this newsgroup as there is no one else I can talk about this. So here's one thing I tried to evolve out of the sources but couldn't find out how it works internally: If you call dir(__builtins__) after starting a python (2.3.4) session you get a list all well known builtin functions. I noticed, that there is already an exit function available as builtin (NOT sys.exit!!). But when you call exit(0) it says TypeError: 'str' object is not callable So I called print __builtins__.exit.__doc__ And surprisingly I got the doc string from str. So I started browsing the sources, and in ./Python/bltinmodule.c there get most of the builtin functions attached to __builtin__, but not the "exit" call. Is it a bug or a feature? exit as builtin is not documented anywhere and I cannot find out where it gets included or attached to the str object in the sources. Any idea? Best regards Oliver