def requestNegotiation(self, about, data):
        """
        Send a negotiation message for the option C{about} with C{data} as the
        payload.

        @param data: the payload
        @type data: L{bytes}
        @see: L{ITelnetTransport.requestNegotiation}
        """
        data = data.replace(IAC, IAC * 2)
        self._write(IAC + SB + about + data + IAC + SE)

        Send a negotiation message for the option C{about} with C{data} as the
        payload.

        @param data: the payload
        @type data: L{bytes}
        @see: L{ITelnetTransport.requestNegotiation}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/telnet.py