def __init__(self, dt1=None, dt2=None,
                 years=0, months=0, days=0, leapdays=0, weeks=0,
                 hours=0, minutes=0, seconds=0, microseconds=0,
                 year=None, month=None, day=None, weekday=None,
                 yearday=None, nlyearday=None,
                 hour=None, minute=None, second=None, microsecond=None):

        if dt1 and dt2:
            # datetime is a subclass of date. So both must be date
            if not (isinstance(dt1, datetime.date) and
                    isinstance(dt2, datetime.date)):
                raise TypeError("relativedelta only diffs datetime/date")

            # We allow two dates, or two datetimes, so we coerce them to be
            # of the same type
            if (isinstance(dt1, datetime.datetime) !=
                    isinstance(dt2, datetime.datetime)):
                if not isinstance(dt1, datetime.datetime):
                    dt1 = datetime.datetime.fromordinal(dt1.toordinal())
                elif not isinstance(dt2, datetime.datetime):
                    dt2 = datetime.datetime.fromordinal(dt2.toordinal())

            self.years = 0
            self.months = 0
            self.days = 0
            self.leapdays = 0
            self.hours = 0
            self.minutes = 0
            self.seconds = 0
            self.microseconds = 0
            self.year = None
            self.month = None
            self.day = None
            self.weekday = None
            self.hour = None
            self.minute = None
            self.second = None
            self.microsecond = None
            self._has_time = 0

            # Get year / month delta between the two
            months = (dt1.year - dt2.year) * 12 + (dt1.month - dt2.month)
            self._set_months(months)

            # Remove the year/month delta so the timedelta is just well-defined
            # time units (seconds, days and microseconds)
            dtm = self.__radd__(dt2)

            # If we've overshot our target, make an adjustment
            if dt1 < dt2:
                compare = operator.gt
                increment = 1
            else:
                compare = operator.lt
                increment = -1

            while compare(dt1, dtm):
                months += increment
                self._set_months(months)
                dtm = self.__radd__(dt2)

            # Get the timedelta between the "months-adjusted" date and dt1
            delta = dt1 - dtm
            self.seconds = delta.seconds + delta.days * 86400
            self.microseconds = delta.microseconds