PYTHON

discord.py cog

from discord.ext import commands

class Ping(commands.Cog):
    """Receives ping commands"""
    
    @commands.command()
    async def ping(self, ctx: commands.Context):
        await ctx.send("Pong")

def setup(bot: commands.Bot):
    bot.add_cog(Ping())

discord.py cog classes

class Test(commands.cog):

    def __init__(self, client):
        self.client = client
        self._last_member = None