def test_iterable(self):
    view = PropertyDictView({'A': 1, 'B': 2, 'C': 3})
    self.assertEqual(set(view), {'A', 'B', 'C'})
def test_iterable(self):
    view = PropertyDictView({'A': 1, 'B': 2, 'C': 3})
    self.assertEqual(set(view), {'A', 'B', 'C'})