def METHOD_NAME(self):
    self.assertEqual(self.props['_DurationDen'], 24)
    with self.assertRaises(KeyError):
        self.props['_NonExistent']
    with self.assertRaises(vs.Error):
        self.props['_DurationDen'] = 1
    with self.assertRaises(vs.Error):
        del self.props['_DurationDen']
    self.assertEqual(self.props['_DurationDen'], 24)
    self.assertEqual(self.props_rw['_DurationDen'], 24)
    self.props_rw['_DurationDen'] = 1
    self.assertEqual(self.props_rw['_DurationDen'], 1)
    del self.props_rw['_DurationDen']
    self.assertFalse('_DurationDen' in self.props_rw)