def test_nullRangeElements(self):
        """
        If there are multiple byte ranges but only one is non-null, the
        non-null range is parsed and its start and stop returned.
        """
        self.assertEqual(
            self.resource._parseRangeHeader(b'bytes=1-2,\r\n, ,\t'), [(1, 2)])

        If there are multiple byte ranges but only one is non-null, the
        non-null range is parsed and its start and stop returned.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py