def test_iteration(self):
        """
        When L{iterbytes} is called with a bytestring, the returned object
        can be iterated over, resulting in the individual bytes of the
        bytestring.
        """
        input = b"abcd"
        result = list(iterbytes(input))
        self.assertEqual(result, [b'a', b'b', b'c', b'd'])

        When L{iterbytes} is called with a bytestring, the returned object
        can be iterated over, resulting in the individual bytes of the
        bytestring.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_compat.py