title: Discord.py Function that responds for all commands
body: <p>I am looking for something like an event that is triggered every time <em>any</em> command is invoked. Something like:</p>
  <pre class="lang-py prettyprint-override"><code>@bot.event
  async def on_command(ctx):
     ...
  </code></pre>
  <p>But I can't find anything for this. Does anyone know how to do this?</p>