def register_except(self, fd, callback):
        """Register `fd` for select.  Will `callback` when executable."""
        assert self._xcallbacks not in fd
        self._xcallbacks[fd] = callback
        self.control(SelectTask.NEWFD)
        #self.logger.debug('Registered %s for except on %d', callback, fd)
dataset/ETHPy150Open facebook/sparts/sparts/tasks/select.py/SelectTask.register_except/swapped operands of `not in`