def test_captureVars(self):
        """
        If startDebugMode() is called, passing captureVars to Failure() will
        not blow up.
        """
        try:
            1/0
        except:
            typ, exc, tb = sys.exc_info()
            f = failure.Failure(captureVars=True)
        self.assertEqual(self.result, [tb])
        self.assertTrue(f.captureVars)

        If startDebugMode() is called, passing captureVars to Failure() will
        not blow up.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_failure.py