def test_add_header_parsing(self):
        """
        When --add-header is specific, the value is parsed.
        """
        options = Options()
        options.parseOptions(
            ['--add-header', 'K1: V1', '--add-header', 'K2: V2']
        )
        self.assertEqual(options['extraHeaders'], [('K1', 'V1'), ('K2', 'V2')])

        When --add-header is specific, the value is parsed.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_tap.py