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 test_bad_isointervals():
    bad_intervals = [
        '2013-01T14:',
        '',
        'asdf',
        '01/01/2013',
    ]

    for bad_interval in bad_intervals:
        yield (
            assert_raises,
            Exception,
            inputs.iso8601interval,
            bad_interval,
        )