def test_nestedTags(self):
        """
        Test that nested tags flatten correctly.
        """
        return self.assertFlattensTo(
            tags.html(tags.body('42'), hi='there'),
            b'<html hi="there"><body>42</body></html>')

        Test that nested tags flatten correctly.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_flatten.py