def test_stringDescription(self):
        """
        L{serverFromString} returns a L{StandardIOEndpoint} instance with a
        'stdio' endpoint string description.
        """
        ep = endpoints.serverFromString(MemoryReactor(), "stdio:")
        self.assertIsInstance(ep, endpoints.StandardIOEndpoint)
        self.assertIsInstance(ep._reactor, MemoryReactor)

        L{serverFromString} returns a L{StandardIOEndpoint} instance with a
        'stdio' endpoint string description.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py