how to make a cog discord py

1from discord.ext import commands
2
3class Test_Cog(commands.Cog):
4	def __init__(self, bot):
5      self.bot = bot # defining bot as global var in class
6      
7	@commands.Cog.listener() # this is a decorator for events/listeners
8    async def on_ready(self):
9      print('Bot is ready!.')
10      
11	@commands.command() # this is for making a command
12    async def ping(self, ctx):
13		await ctx.send(f'Pong! {round(self.bot.latency * 1000)}')
14        
15def setup(bot): # a extension must have a setup function
16	bot.add_cog(Test_Cog(bot)) # adding a cog

1class Test(commands.cog):
2
3    def __init__(self, client):
4        self.client = client
5        self._last_member = None