我有一个简单的代码：

import discord
import threading #just prepare for future use
import subprocess # prepare also
client = discord.Client()

@client.event
async def on_ready():
    print('ready')
async def on_message(message):
    return message.channel.send(message)

client.run('TOKENNNNNN')

但是当我尝试运行此代码时，我收到了以下追溯信息：

Traceback (most recent call last):
  File "D:/python/projects/Discord bot.py",line 6,in <module>
    import discord
  File "D:\python\block shooter\venv\lib\site-packages\discord\__init__.py",line 23,in <module>
    from .client import Client
  File "D:\python\block shooter\venv\lib\site-packages\discord\client.py",line 27,in <module>
    import asyncio
  File "C:\Users\Edison\AppData\Local\Programs\Python\Python37-32\Lib\asyncio\__init__.py",line 8,in <module>
    from .base_events import *
  File "C:\Users\Edison\AppData\Local\Programs\Python\Python37-32\Lib\asyncio\base_events.py",line 39,in <module>
    from . import events
  File "C:\Users\Edison\AppData\Local\Programs\Python\Python37-32\Lib\asyncio\events.py",line 14,in <module>
    import contextvars
  File "C:\Users\Edison\AppData\Local\Programs\Python\Python37-32\Lib\contextvars.py",line 1,in <module>
    from _contextvars import Context,ContextVar,Token,copy_context
ModuleNotFoundError: No module named '_contextvars'

我认为这与_contextvars有关，所以我尝试安装contextvars，但似乎无法正常工作……有人可以帮助我吗？