youtube-dl完成下载后，运行异步功能（python）

问题描述：

我一直在使用discord.py重写为python编写音乐bot。它通过youtube-
dl下载视频并通过语音聊天播放。我一直在努力扩展音乐，最近发现我完全忽略了某些东西。progress hooksyoutube-
dl的选项是同步的，而discord.py是异步的。youtube-
dl在下载视频时会生成一个子进程，而不是在当前线程上运行它，因此它不会挂起程序。下载完成后需要运行的功能是协程，因为它是discord.py的一部分

TL; DR，当youtube-dl下载完成时，我需要运行协程

我知道这是可能的，我之前已经看过它，但是不太了解。

这是我到目前为止的内容：

def log(text):
  print(Style.BRIGHT + Fore.WHITE + '[' + Fore.RED + 'Music' + Fore.WHITE + '] ' + Style.RESET_ALL + text)
def sync_config():
  raw_config.seek(0)
  raw_config.write(json.dumps(config))
  raw_config.truncate()
lookup_opts = {
    "simulate": True,
    "quiet" : True, #TODO: make this part of config.json
}

if not os.path.exists("plugins/music"):
  log("Config does not exist! Creating it for you..")
  os.makedirs("plugins/music")
if not os.path.exists("plugins/music/cache"):
  os.makedirs("plugins/music/cache")
if not os.path.exists("plugins/music/config.json"):
    with open('plugins/music/config.json', 'w+') as f:
      f.write('{}')
      log('Created config.json')
raw_config = open('plugins/music/config.json', 'r+')
config = json.load(raw_config)

class Music:
  def __init__(self, bot):
      self.bot = bot
  @commands.command(hidden=True)
  async def clearcache(self, ctx):
    if ctx.author.id in ctx.bot.config["admins"]:
      log("Cache cleared!")
      await ctx.message.add_reaction("✅")
      shutil.rmtree("plugins/music/cache")
      os.makedirs("plugins/music/cache")
    else:
      await ctx.send(ctx.bot.denied())
  @commands.command()
  async def play(self, ctx, url):
    """Download and play a link from youtube"""
    message = await ctx.send(f"Downloading <{url}>..")
    with youtube_dl.YoutubeDL(lookup_opts) as ydl:
      try:
        info = ydl.extract_info(url)
        await message.edit(content=f"Downloading {info['title']}..")
      except:
        await ctx.send("An error occured downloading that video! Are you sure that URL is correct?")
      def callback(d):
        if d['status'] == 'finished':
              loop = asyncio.new_event_loop()
              asyncio.set_event_loop(loop)
              loop.run_until_complete(ctx.send("Done!"))
              print("Done!")
      download_opts = {
        "format": 'm4a/bestaudio/best',
        "quiet" : True, #TODO: make this part of config.json
        'progress_hooks': [callback],
      }
      with youtube_dl.YoutubeDL(download_opts) as ydl:
          ydl.download([url])

我知道这在python 2.6中很容易实现。但是在Python 2.5中最简单的方法是什么？x = "This is my string"b = to_bytes(x) # I could do ...