def _ebCheckKey(self, reason, packet):
        """
        Called back if the user did not sent a signature.  If reason is
        error.ValidPublicKey then this key is valid for the user to
        authenticate with.  Send MSG_USERAUTH_PK_OK.
        """
        reason.trap(error.ValidPublicKey)
        # if we make it here, it means that the publickey is valid
        self.transport.sendPacket(MSG_USERAUTH_PK_OK, packet)
        return failure.Failure(error.IgnoreAuthentication())

        Called back if the user did not sent a signature.  If reason is
        error.ValidPublicKey then this key is valid for the user to
        authenticate with.  Send MSG_USERAUTH_PK_OK.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/userauth.py