def watch_prefix_once(self, key_prefix, timeout=None, **kwargs):
        """
        Watches a range of keys with a prefix and stops after the first event.

        If the timeout was specified and event didn't arrived method
        will raise ``WatchTimedOut`` exception.
        """
        kwargs['range_end'] = \
            utils.increment_last_byte(utils.to_bytes(key_prefix))
        return self.watch_once(key_prefix, timeout=timeout, **kwargs)
Watches a range of keys with a prefix and stops after the first event.

        If the timeout was specified and event didn't arrived method
        will raise ``WatchTimedOut`` exception.