Class AnextOnly

Lib/test/test_collections.py:962–964

            self.assertNotIsSubclass(type(x), AsyncIterator)
        # Similarly to regular iterators (see issue 10565)
        class AnextOnly:
            async def __anext__(self):
                raise StopAsyncIteration
        self.assertNotIsInstance(AnextOnly(), AsyncIterator)
        self.validate_abstract_methods(AsyncIterator, '__anext__')