def sendall_stderr(self, s):
        """
        Send data to the channel's "stderr" stream, without allowing partial
        results.  Unlike `send_stderr`, this method continues to send data
        from the given string until all data has been sent or an error occurs.
        Nothing is returned.

        :param str s: data to send to the client as "stderr" output.

        :raises socket.timeout:
            if sending stalled for longer than the timeout set by `settimeout`.
        :raises socket.error:
            if an error occurred before the entire string was sent.

        .. versionadded:: 1.1
        """
        while s:
            sent = self.send_stderr(s)
            s = s[sent:]
        return None