title: Discord.py Check if Channel is a DM
body: <p>I am creating a command that i only want to be executable through a DM with the bot. The current code makes it possible to send the command to any channel, i want to prevent this.</p>
  
  <pre><code>@client.command()
  async def check(ctx, arg):
      if discord.ChannelType.private:
          await ctx.send(arg)
  </code></pre>
  
  <p>I've also tried: <strong>discord.ChannelType == discord.ChannelType.private</strong> &amp; <strong>discord.DMChannel</strong></p>