Filter.py

import discord
from discord.ext import commands

class Filter:
    def __init__(self, client):
        self.client = client

    async def on_message(self,message):
        filter_words= ["NIGGER", "NIGGA", "FAGGOT", "RETARDED","CUNT", "KYS","FUCK"] #Words to filter
        MakeWordsUpper=message.content.upper() 
        for word in filter_words:
            if word in MakeWordsUpper: #checks if the message sent contains any word from the filter_words
                    await self.client.delete_message(message) #Deletes the message 
                    await self.client.send_message(message.channel, "You're not allowed to use that word here!")
        
      
def setup(client):
    client.add_cog(Filter(client))