def _sd_handler(self, desc_type, unit, desc, show_on_keypad):
        """Text description"""
        if desc_type not in self._descriptions_in_progress:
            LOG.debug("Text description response ignored for " + str(desc_type))
            return

        (max_units, results, callback) = self._descriptions_in_progress[desc_type]
        if unit < 0 or unit >= max_units:
            callback(results)
            del self._descriptions_in_progress[desc_type]
            return

        results[unit] = desc
        self.send(sd_encode(desc_type=desc_type, unit=unit+1))
Text description