def _ebMaybeBadAuth(self, reason):
        """
        An intermediate errback.  If the reason is
        error.NotEnoughAuthentication, we send a MSG_USERAUTH_FAILURE, but
        with the partial success indicator set.

        @type reason: L{twisted.python.failure.Failure}
        """
        reason.trap(error.NotEnoughAuthentication)
        self.transport.sendPacket(MSG_USERAUTH_FAILURE,
                NS(b','.join(self.supportedAuthentications)) + b'\xff')

        An intermediate errback.  If the reason is
        error.NotEnoughAuthentication, we send a MSG_USERAUTH_FAILURE, but
        with the partial success indicator set.

        @type reason: L{twisted.python.failure.Failure}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/userauth.py