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_abstract_class(self):
        class X(Structure):
            _abstract_ = "something"
        # try 'X()'
        cls, msg = self.get_except(eval, "X()", locals())
        self.assertEqual((cls, msg), (TypeError, "abstract class"))