好的，所以我有这段代码，但是当我尝试使用$ announce时，它不会写回Hello。实际上，它不响应我在异步定义下所做的任何事情。怎么会来？

我觉得我已经正确地完成了所有操作，这些教程是为了重写和使用我正在使用的教程。

import discord
from discord.ext import commands
import os
import time
import random
import weather
from weather import Weather,Unit

prefix = '$'
client = commands.Bot(command_prefix = prefix)
clattr = discord.Client()


@client.event
async def on_ready():
        await client.change_presence(status = discord.Status.online,activity = discord.Game('have a nice day!'))
        print("Bot is now online!")


@client.event
async def on_message(message):
  if message.content.startswith("$hello"):
    await message.channel.send(f"""Hi""")
    await message.channel.send(f"""Hi""")
    await message.channel.send(f"""Hi""")
    await message.channel.send(f"""Hi""")
    await message.channel.send(f"""Hi""")
    await message.channel.send(f"""Hi""")
    await message.channel.send(time())
  if message.content.startswith("$dm"): 
    user = client.get_user(393921960817721355)
    dm_channel = user.dm_channel
    if (dm_channel==None):
      dm_channel = await user.create_dm()
    await dm_channel.send(f"""Hello!""")
  if message.content.startswith("$servers"):
    await message.channel.send(clattr.guilds)
  if message.content.startswith("$help"):
    await message.channel.send(f"""This is the vanceBot. Made by vance and OYOHO#5964 (xray#4398 helped as well).\nThese are the current commands:\n$hello,which says "Hi" a few times \n$dm,which DMs a person\n$servers,which displays the number of servers that the bot is on\n$leave,to get the bot to leave\n$help,this command.\nThe prefix is $.""")
  if message.content.startswith("$pinghelp"):
    await message.channel.send(f"""||@everyone|| This is the vanceBot. Made by vance and OYOHO#5964 (xray#4398 helped as well).\nThese are the current commands:\n$hello,this command.\nThe prefix is $.""")


@client.command()
async def announce(ctx,announcement):
  await ctx.send(f"""Hello""")




TOKEN = os.environ.get("DISCORD_BOT_SECRET")
client.run(TOKEN)