test_futures.py:296:            x = yield from f
test_futures.py:298:            y = yield from f
test_futures.py:303:        self.assertEqual(next(g), f)  # First yield from f.
test_futures.py:306:        # The second "yield from f" does not yield f.
test_futures.py:408:            yield from fut
test_pep492.py:152:            yield from ()
test_sslproto.py:99:        # yield from waiter hang if lost_connection was called.
test_tasks.py:2096:                return (yield from fut)
utils.py:271:            yield from _run_test_server(address=path, use_ssl=use_ssl,
utils.py:278:    yield from _run_test_server(address=(host, port), use_ssl=use_ssl,