Python Dicord.py运行时错误：无法关闭正在运行的事件循环

我正在测试创建一个简单的discord机器人，并粘贴了这本教科书代码来测试它：

import os

import discord
from dotenv import load_dotenv

load_dotenv()
TOKEN = os.getenv('DISCORD_TOKEN')

client = discord.Client()

@client.event
async def on_ready():
    print(f'{client.user} has connected to Discord!')
client.run(TOKEN)

但我得到了以下错误：

/usr/local/lib/python3.6/dist-packages/discord/client.py in run(self, *args, **kwargs)
702             future.remove_done_callback(stop_loop_on_completion)
703             log.info('Cleaning up tasks.')
--> 704             _cleanup_loop(loop)
    705 
    706         if not future.cancelled():

/usr/local/lib/python3.6/dist-packages/discord/client.py in _cleanup_loop(loop)
     95     finally:
     96         log.info('Closing the event loop.')
---> 97         loop.close()
     98 
     99 class _ClientEventTask(asyncio.Task):

/usr/lib/python3.6/asyncio/unix_events.py in close(self)
     61 
     62     def close(self):
---> 63         super().close()
     64         if not sys.is_finalizing():
     65             for sig in list(self._signal_handlers):

/usr/lib/python3.6/asyncio/selector_events.py in close(self)
     94     def close(self):
     95         if self.is_running():
---> 96             raise RuntimeError("Cannot close a running event loop")
     97         if self.is_closed():
     98             return

RuntimeError: Cannot close a running event loop

我尝试了各种解决方案和安装，但似乎没有任何效果。 这是在google collaboratory上运行的。 提前感谢您的回答