def run(action, music=None, value=0, delta=False, **kwargs): for music in action.music_list(music): music.seek(value=value, delta=delta) def description(action, music=None, value=0, delta=False, **kwargs): if delta: if music is not None: return "moving music « {} » by {:+d}s" \ .format(music.name, value) else: return "moving all musics by {:+d}s" \ .format(value) else: if music is not None: return "moving music « {} » to position {}s" \ .format(music.name, value) else: return "moving all musics to position {}s" \ .format(value)