title: discord.py bot doesnt respond to Bot.commands()
body: <p>Hello I am creating a discord bot i was trying to add single command but bot doesn't respond to any commands</p>
  
  <p>something like</p>
  
  <pre><code>Bot = commands.Bot(command_prefix="!")
  @Bot.commands()
  async def ping():
      print("Pong!")
  </code></pre>
  
  <p>this thing should respond when I type !ping in to discord client it should print pong in to terminal
  but nothing nothing at all
  I have tried Bot.add_command(ping) but it says command it's aleady registered i have no idea..</p>