def _get_matrix(self):
        if not hasattr(self, "_contrast_matrix"):
            self.compute_matrix()
        return self._contrast_matrix
A new MyPerson also shows up as a standard Person.
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/stats/contrast.py/Contrast._get_matrix--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/tests/modeltests/proxy_models/tests.py/ProxyModelTests.test_basic_proxy_reverse