ExitStack.__exit__

gistfile1.py

    
    def __exit__(self, *exc_details):
        if not self._exit_callbacks:
            return
        for cb in reversed(self._exit_callbacks):
            try:
                supress_exc = cb(*exc_details)
            except:
                exc_details = sys.exc_info()
            else:
                if supress_exc:
                    exc_details = (None, None, None)
        self._exit_callbacks = deque()
        return supress_exc or exc_details == (None, None, None)