edits.py

import asyncio

import discord


class MyClient(discord.Client):
    async def on_ready(self):
        print(f"Logged in as {self.user} (ID: {self.user.id})")
        print("------")

    async def on_message(self, message):
        if message.content.startswith("!editme"):
            msg = await message.channel.send("10")
            await asyncio.sleep(3.0)
            await msg.edit(content="40")

    async def on_message_edit(self, before, after):
        msg = f"**{before.author}** edited their message:\n{before.content} -> {after.content}"
        await before.channel.send(msg)


client = MyClient()
client.run("token")