def handle_APOP(self, line):
        """
        Require an I{OK} response to I{APOP}.

        @param line: The I{APOP} response.
        """
        parts = line.split()
        code = parts[0]
        if code != b'+OK':
            raise AssertionError('code is: %s , parts is: %s ' % (code, parts))
        self.lines = []
        self.retr(1)

        Require an I{OK} response to I{APOP}.

        @param line: The I{APOP} response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_pop3.py