def __init__(self, children, connector, negated=False):
        if len(children) != 2:
            raise TypeError('Must specify a node and a timedelta.')
        if not isinstance(children[1], datetime.timedelta):
            raise TypeError('Second child must be a timedelta.')
        if connector not in (self.ADD, self.SUB):
            raise TypeError('Connector must be + or -, not %s' % connector)
        super(DateModifierNode, self).__init__(children, connector, negated)
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/expressions.py/DateModifierNode.__init__/original