Python - DM A User Discord Bot

I'm working on a User Discord Bot in Python .If the bot owner types !DM @user then the bot will DM the user that was mentioned by the owner.

@client.event
async def on_message(message):
    if message.content.startswith('!DM'):
        msg = 'This Message is send in DM'
        await client.send_message(message.author, msg)

The easiest way to do this is with the discord.ext.commands extension. Here we use a converter to get the target user, and a keyword-only argument as an optional message to send them:

from discord.ext import commands
import discord

bot = commands.Bot(command_prefix='!')

@bot.command(pass_context=True)
async def DM(ctx, user: discord.User, *, message=None):
    message = message or "This Message is sent via DM"
    await bot.send_message(user, message)

bot.run("TOKEN")

For the newer 1.0+ versions of discord.py, you should use send instead of send_message

from discord.ext import commands
import discord

bot = commands.Bot(command_prefix='!')

@bot.command()
async def DM(ctx, user: discord.User, *, message=None):
    message = message or "This Message is sent via DM"
    await user.send(message)

bot.run("TOKEN")