def test_versionMetadata(self):
        """
        Deprecating a function adds version information to the decorated
        version of that function.
        """
        version = Version('Twisted', 8, 0, 0)
        dummy = deprecated(version)(dummyCallable)
        self.assertEqual(version, dummy.deprecatedVersion)

        Deprecating a function adds version information to the decorated
        version of that function.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_deprecate.py