Discord.pyでサーバーで有効な招待URLを表示したい

リファレンスを見ながら書いていますが仕様がわからずつまづいています。
実行したサーバーでの使える招待URLのリストを表示させたいです

ソースコード

py
1@bot.command()
2async def invitelink(ctx):
3    invis = await fetch_invite(ctx.author.guild.id)
4    await ctx.send(invis)

エラー

Ignoring exception in command invitelink:
Traceback (most recent call last):
  File "/opt/virtualenvs/python3/lib/python3.8/site-packages/discord/ext/commands/core.py", line 85, in wrapped
    ret = await coro(*args, **kwargs)
  File "main.py", line 106, in invitelink
    invis = await fetch_invite(ctx.author.guild.id)
NameError: name 'fetch_invite' is not defined

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/virtualenvs/python3/lib/python3.8/site-packages/discord/ext/commands/bot.py", line 939, in invoke
    await ctx.command.invoke(ctx)
  File "/opt/virtualenvs/python3/lib/python3.8/site-packages/discord/ext/commands/core.py", line 863, in invoke
    await injected(*ctx.args, **ctx.kwargs)
  File "/opt/virtualenvs/python3/lib/python3.8/site-packages/discord/ext/commands/core.py", line 94, in wrapped
    raise CommandInvokeError(exc) from exc
discord.ext.commands.errors.CommandInvokeError: Command raised an exception: NameError: name 'fetch_invite' is not defined