def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
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"))