def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def test_execute(self):
        opt = Optional(None, execute=dict)
        self.assertEqual(deoption(opt), {})
        self.assertEqual(deoption(opt, execute=dict), {})
        self.assertEqual(deoption(None, execute=dict), {})