Method __aexit__

Lib/test/test_coroutines.py:1215–1220

(self, *args)

                return self

            async def __aexit__(self, *args):
                await AsyncYieldFrom(['exit-1-' + self.name,
                                      'exit-2-' + self.name])

                if self.name == 'B':
                    return True


        async def foo():