如何在discord.py中获取用户活动？

import discord
from discord.ext import commands

intents = discord.Intents.default()
intents.presences = True

bot = commands.Bot(command_prefix='!', intents=intents)

@bot.event
async def on_member_update(before, after):
    if before.activity != after.activity:
        activity = after.activity
        if isinstance(activity, discord.Game):
            print(f'{after.name}正在玩 {activity.name}')
        elif isinstance(activity, discord.Streaming):
            print(f'{after.name}正在直播 {activity.name}')
        elif isinstance(activity, discord.Spotify):
            print(f'{after.name}正在听 {activity.title}')
        # 其他活动类型的判断...

bot.run('YOUR_BOT_TOKEN')