def test_default(self):
        """
        L{None} values can be added to a list to cause it to have a certain
        length.
        """
        padded = util.padTo(3, [])
        self.assertEqual([None] * 3, padded)

        L{None} values can be added to a list to cause it to have a certain
        length.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_util.py