def test_rangeMissingStart(self):
        """
        A single bytes range without an explicit start position is parsed into
        a two-tuple of L{None} and the end position.
        """
        self.assertEqual(
            self.resource._parseRangeHeader(b'bytes=-3'), [(None, 3)])

        A single bytes range without an explicit start position is parsed into
        a two-tuple of L{None} and the end position.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_static.py