如何修复运行时错误:无法关闭正在运行的事件循环 - Python Discord Bot

I am trying to create a Discord bot with Python, however whenever I run the sample code here:

import discord

client = discord.Client()

@client.event
async def on_message(message):
    # we do not want the bot to reply to itself
    if message.author == client.user:
        return

    if message.content.startswith('!hello'):
        msg = 'Hello {0.author.mention}'.format(message)
        await client.send_message(message.channel, msg)

@client.event
async def on_ready():
    print('Logged in as')
    print(client.user.name)
    print(client.user.id)
    print('------')

client.run('tokenhere')

返回错误:

Traceback (most recent call last):

  File "<ipython-input-6-ea5a13e5703d>", line 1, in <module>
    runfile('C:/Users/User/Pictures/rito_bot.py', wdir='C:/Users/User/Pictures')

  File "C:UsersUserAnaconda3libsite-packagesspyder_kernelscustomizespydercustomize.py", line 703, in runfile
    execfile(filename, namespace)

  File "C:UsersUserAnaconda3libsite-packagesspyder_kernelscustomizespydercustomize.py", line 108, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/User/Pictures/rito_bot.py", line 22, in <module>
    client.run('token')

  File "C:UsersUserAnaconda3libsite-packagesdiscordclient.py", line 595, in run
    _cleanup_loop(loop)

  File "C:UsersUserAnaconda3libsite-packagesdiscordclient.py", line 97, in _cleanup_loop
    loop.close()

  File "C:UsersUserAnaconda3libasyncioselector_events.py", line 94, in close
    raise RuntimeError("Cannot close a running event loop")

RuntimeError: Cannot close a running event loop 

其他每一行似乎都运行得很好，但是如果没有最后一行，它就无法连接到服务器，这使得它毫无用处.