我目前的目标是为我的私人Disord Server创建一个可以播放. mp3文件的Disord Bot。这是我的代码。文件test.mp3与.py文件位于同一文件夹中。错误消息是：“NameError：name'FFmpegPCMAudio'未定义”。我在路径环境变量中添加了ffmpeg可执行文件。有人能帮忙吗？

import discord
import asyncio
import time

client = discord.Client()

@client.event
async def on_message(message):
    if "test" in message.content:
        user = message.author
        voice_channel = user.voice.channel
        channel = None
        if voice_channel != None:
            channel = voice_channel.name
            vc = await voice_channel.connect()
            player = vc.play(FFmpegPCMAudio("test.mp3"), after=lambda: print('done'))
            player.start()
            while not player.is_done():
                await asyncio.sleep(1)
            player.stop()
            await vc.disconnect()

client.run(TOKEN)