def test_headers(self):
        """
        The headers passed to the I{start_response} callable are included in
        the response as are the required I{Date} and I{Server} headers and the
        necessary connection (hop to hop) header I{Transfer-Encoding}.
        """
        return self._headersTest(
            [('foo', 'bar'), ('baz', 'quux')],
            [b'Baz: quux', b'Foo: bar'])

        The headers passed to the I{start_response} callable are included in
        the response as are the required I{Date} and I{Server} headers and the
        necessary connection (hop to hop) header I{Transfer-Encoding}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_wsgi.py