    def __datetime_to_epoch(self, date_time):
        """
        Converts a python datetime to unix epoch, accounting for
        time zones and such.

        Assumes UTC if timezone is not given.
        """
        date_time_utc = None
        if date_time.tzinfo is None:
            date_time_utc = date_time.replace(tzinfo=pytz.utc)
        else:
            date_time_utc = date_time.astimezone(pytz.utc)

        epoch_utc = datetime.datetime.utcfromtimestamp(0).replace(tzinfo=pytz.utc)

        return (date_time_utc - epoch_utc).total_seconds()