def delete(self, session_key=None):
        if session_key is None:
            if self.session_key is None:
                return
            session_key = self.session_key
        try:
            os.unlink(self._key_to_file(session_key))
        except __HOLE__:
            pass
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/sessions/backends/file.py/SessionStore.delete