def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def get_date(self, p_tag):
        """ Given a date tag, return a date object. """
        string = self.tag_value(p_tag)
        result = None

        try:
            result = date_string_to_date(string) if string else None
        except ValueError:
            pass

        return result