Erreur dans mon bot Discord avec Python

import discord
from discord.ext import commands

TOKEN = 'Je vais quand même pas vous dire le Token de mon bot xD'

description = '''Bot Python'''
bot = commands.Bot(command_prefix='?', description=description)

@bot.event
async def on_ready():
    print('Logged in as')
    print(bot.user.name)
    print(bot.user.id)
    print('------')

@bot.command()
async def hello():
    """Says Hello World"""
    await bot.say("Hellod")

bot.run(TOKEN)

Traceback (most recent call last):
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\client.py", line 270, in _run_event
    await coro(*args, **kwargs)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\bot.py", line 901, in on_message
    await self.process_commands(message)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\bot.py", line 898, in process_commands
    await self.invoke(ctx)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\bot.py", line 863, in invoke
    await ctx.command.invoke(ctx)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\core.py", line 721, in invoke
    await self.prepare(ctx)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\core.py", line 685, in prepare
    await self._parse_arguments(ctx)
  File "C:\Users\tomba\AppData\Local\Programs\Python\Python37\lib\site-packages\discord\ext\commands\core.py", line 595, in _parse_arguments
    raise discord.ClientException(fmt.format(self))
discord.errors.ClientException: Callback for hello command is missing "ctx" parameter.