def test_exist(self):
        """
        All modules listed in L{notPortedModules} exist on Py2.
        """
        root = os.path.dirname(os.path.dirname(twisted.__file__))
        for module in notPortedModules:
            segments = module.split(".")
            segments[-1] += ".py"
            path = os.path.join(root, *segments)
            alternateSegments = module.split(".") + ["__init__.py"]
            packagePath = os.path.join(root, *alternateSegments)
            self.assertTrue(os.path.exists(path) or
                            os.path.exists(packagePath),
                            "Module {0} does not exist".format(module))

        All modules listed in L{notPortedModules} exist on Py2.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_dist3.py