In contextlib, there is code which roughly looks like def _exit_wrapper(exc_type, exc, tb): return cm_exit(cm, exc_type, exc, tb) _exit_wrapper.__self__ = cm This creates a new function _exit_wrapper from a given function cm_exit by prepending the __self__ attribute to *args. Now this is exactly what a method does too. It would be better to use an actual method for this: it's cleaner, faster and it doesn't abuse a double-underscore attribute. The latter will actually break with PEP 575, as __self__ will become a special name instead of an arbitrary attribute.
Yury, could you double check the async exit stack change in the PR? I think it's fine since the bound method just passes back the underlying coroutine and the tests all still pass, but a second opinion would be good :)
