def _get_delta(self, now, then):
        """
        Internal helper which will return a ``datetime.timedelta``
        representing the time between ``now`` and ``then``. Assumes
        ``now`` is a ``datetime.date`` or ``datetime.datetime`` later
        than ``then``.

        If ``now`` and ``then`` are not of the same type due to one of
        them being a ``datetime.date`` and the other being a
        ``datetime.datetime``, both will be coerced to
        ``datetime.date`` before calculating the delta.

        """
        if now.__class__ is not then.__class__:
            now = datetime.date(now.year, now.month, now.day)
            then = datetime.date(then.year, then.month, then.day)
        if now < then:
            raise ValueError("Cannot determine moderation rules because date field is set to a value in the future")
        return now - then
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/comments/moderation.py/CommentModerator._get_delta/original