如何在discord.py库中设置多个前缀或使前缀不区分大小写？

import discord
from discord.ext import commands

bot = commands.Bot(command_prefix=['!', '$', '.'])

@bot.event
async def on_ready():
    print(f'Logged in as {bot.user.name}')

@bot.command()
async def hello(ctx):
    await ctx.send('Hello!')

bot.run('YOUR_BOT_TOKEN')

import discord
from discord.ext import commands

class CaseInsensitivePrefix(commands.PrefixConverter):
    async def convert(self, ctx, argument):
        return argument.lower()

bot = commands.Bot(command_prefix=CaseInsensitivePrefix())

@bot.event
async def on_ready():
    print(f'Logged in as {bot.user.name}')

@bot.command()
async def hello(ctx):
    await ctx.send('Hello!')

bot.run('YOUR_BOT_TOKEN')