how to load a all cogs automatically 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

1# bot file
2import os
3from discord.ext import commands
4
5bot = commands.Bot(command_prefix='.')
6# I am assuming that you have a test.py cog in a cogs folder
7bot.load_extension('cogs.test') # this is good but you can make it better
8
9for filename in os.listdir('./cogs'):
10  if filename.endswith('.py'):
11    bot.load_extension(f'cogs.{filename[:-3]}')
12    
13  else:
14    print(f'Unable to load {filename[:-3]}')
15    
16bot.run(token)