def test_lenientPrefixBehavior(self):
        """
        If the parser sees a prefix it doesn't recognize on an attribute, it
        will pass it on through to serialization.
        """
        theInput = (
            '<hello:world hello:sample="testing" '
            'xmlns:hello="http://made-up.example.com/ns/not-real">'
            'This is a made-up tag.</hello:world>')
        element = Element(loader=XMLString(theInput))
        self.assertFlattensTo(element, theInput.encode('utf8'))

        If the parser sees a prefix it doesn't recognize on an attribute, it
        will pass it on through to serialization.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_template.py