Class InternalMapping

Lib/test/test_str.py:1423–1427

        self.assertEqual('{a} {world}'.format_map(Mapping(a='hello')), 'hello world')

        class InternalMapping:
            def __init__(self):
                self.mapping = {'a': 'hello'}
            def __getitem__(self, key):
                return self.mapping[key]
        self.assertEqual('{a}'.format_map(InternalMapping()), 'hello')