title: How to get message by id discord.py
body: <p>I'm wondering how to get a message by its message id. I have tried <code>discord.fetch_message(id)</code> and <code>discord.get_message(id)</code>, but both raise:</p>
  <pre><code>Command raised an exception: AttributeError: module 'discord' has no attribute 'fetch_message'/'get_message'
  </code></pre>