How to use the catt.util.warning function in catt

def save(settings, path):
    cst = setup_cast(settings["device"], prep="control")
    if not cst.save_capability or cst.is_streaming_local_file:
        raise CliError("Saving state of this kind of content is not supported")
    elif cst.save_capability == "partial":
        warning("Please be advised that playlist data will not be saved")

    print_status(cst.media_info)
    if path and path.is_file():
        click.confirm("File already exists. Overwrite?", abort=True)
    click.echo("Saving...")
    if path:
        state = CastState(path, StateMode.ARBI)
        cc_name = "*"
    else:
        state = CastState(STATE_PATH, StateMode.CONF)
        cc_name = cst.cc_name
    state.set_data(cc_name, {"controller": cst.name, "data": cst.media_info})

if strict:
            raise AppSelectionError("App not found (strict is set)")
        else:
            return DEFAULT_APP

    if app.name == "default":
        return app

    if not cast_type:
        raise AppSelectionError("Cast type is needed for app selection")
    elif cast_type not in app.supported_device_types:
        msg = "The {} app is not available for this device".format(app.name.capitalize())
        if strict:
            raise AppSelectionError("{} (strict is set)".format(msg))
        elif show_warning:
            warning(msg)
        return DEFAULT_APP
    else:
        return app

if stream.is_local_file:
        fail_if_no_ip(stream.local_ip)
        st_thr = create_server_thread(
            video_url, stream.local_ip, stream.port, stream.guessed_content_type, single_req=media_is_image
        )
    elif stream.is_playlist and not (no_playlist and stream.video_id):
        if stream.playlist_length == 0:
            cst.kill(idle_only=True)
            raise CliError("Playlist is empty")
        if not random_play and cst.playlist_capability and stream.playlist_all_ids:
            playlist_playback = True
        else:
            if random_play:
                entry = random.randrange(0, stream.playlist_length)
            else:
                warning("Playlist playback not possible, playing first video")
                entry = 0
            stream.set_playlist_entry(entry)

    if playlist_playback:
        click.echo("Casting remote playlist {}...".format(video_url))
        video_id = stream.video_id or stream.playlist_all_ids[0]
        cst.play_playlist(stream.playlist_id, video_id=video_id)
    else:
        if not subtitles and not no_subs and stream.is_local_file:
            subtitles = hunt_subtitles(video_url)
        if subtitles:
            fail_if_no_ip(stream.local_ip)
            subs = SubsInfo(subtitles, stream.local_ip, stream.port + 1)
            su_thr = create_server_thread(
                subs.file, subs.local_ip, subs.port, "text/vtt;charset=utf-8", single_req=True
            )