Downloads a playlist

def download_playlist(playlist):
    """
    Downloads a playlist
    """
    global arguments
    invalid_chars = '\/:*?|<>"'
    playlist_name = playlist['title'].encode('utf-8', 'ignore')
    playlist_name = playlist_name.decode('utf8')
    playlist_name = ''.join(c for c in playlist_name if c not in invalid_chars)

    if not arguments['--no-playlist-folder']:
        if not os.path.exists(playlist_name):
            os.makedirs(playlist_name)
        os.chdir(playlist_name)

    try:
        with codecs.open(playlist_name + '.m3u', 'w+', 'utf8') as playlist_file:
            playlist_file.write('#EXTM3U' + os.linesep)
            del playlist['tracks'][:offset - 1]
            for counter, track_raw in enumerate(playlist['tracks'], offset):
                logger.debug(track_raw)
                logger.info('Track n°{0}'.format(counter))
                download_track(track_raw, playlist['title'], playlist_file)
    finally:
        os.chdir('..')