def test_setScrollRegionJustFirst(self):
        """
        With just a value for its C{first} argument,
        L{ServerProtocol.setScrollRegion} writes a control sequence with
        that parameter, a parameter separator, and finally a C{b'r'}.
        """
        self.protocol.setScrollRegion(first=1)
        self.assertEqual(self.transport.value(), self.CSI + b'1;' + b'r')

        With just a value for its C{first} argument,
        L{ServerProtocol.setScrollRegion} writes a control sequence with
        that parameter, a parameter separator, and finally a C{b'r'}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_insults.py