def __init__(self, *args, **kwargs):
        kwargs.setdefault('default', now)
        monitor = kwargs.pop('monitor', None)
        if not monitor:
            raise TypeError(
                self.__class__.__name__ % '%s requires a "monitor" argument')
        self.monitor = monitor
        when = kwargs.pop('when', None)
        if when is not None:
            when = set(when)
        self.when = when
        super(MonitorField, self).__init__(*args, **kwargs)
dataset/ETHPy150Open carljm/django-model-utils/model_utils/fields.py/MonitorField.__init__/swapped operands of `%`