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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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