我如何在discordpy中获得机器人(客户端)的顶级角色？

import discord
from discord.ext import commands

bot = commands.Bot(command_prefix='!')
bot.run('YOUR_BOT_TOKEN')

@bot.event
async def on_ready():
    print('Bot is ready!')

@bot.event
async def on_ready():
    print('Bot is ready!')
    for guild in bot.user.guilds:
        print(guild.name)

@bot.event
async def on_ready():
    print('Bot is ready!')
    for guild in bot.user.guilds:
        print(guild.name)
        for role in guild.me.roles:
            print(role.name)