Byteplay lets you convert Python code objects into equivalent objects which are easy to play with, and lets you convert those objects back into living Python code objects. It's useful for applying crazy transformations on Python functions, and is also useful in learning Python byte code intricacies. Check the documentation to see it in action!

Byteplay was written by Noam Yorav-Raphael. Support for Python 2.6 and 2.7 was added by Greg X. Iain Lowe is maintaining and packaging byteplay for 2.x. Support for Python 3.x was added by Andrew Barnert.

Byteplay is pretty reliable - Python's complete test suite continues to pass after you use byteplay to disassemble all the code in the standard library and assemble it again!

Well, that's with 2.5. With 2.6+, various things don't work right inside certain combinations of try and with statements. For 2.x, only continue seems to be affected, and there's a hacky fix for that. For 3.x, there are additional problems with continue, again hackily fixed, and also for yield from, and possibly other things. At present, you can't even reassemble the entire stdlib (although it's pretty close).