def test_readlineTwice(self):
        """
        Calling L{_InputStream.readline} a second time returns the line
        following the line returned by the first call.
        """
        bytes = b"first line\nsecond line\nlast line"
        def readline(input):
            input.readline()
            return input.readline()
        d = self._renderAndReturnReaderResult(readline, bytes)
        d.addCallback(self.assertEqual, b"second line\n")
        return d

        Calling L{_InputStream.readline} a second time returns the line
        following the line returned by the first call.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_wsgi.py