title: RabbitMQ def callback(ch, method, properties, body)
body: <p>Just want to know the meaning of the parameters in <code>worker.py</code> file:</p>
  <pre><code>def callback(ch, method, properties, body):
      print &quot; [x] Received %r&quot; % (body,)
  </code></pre>
  <p>What do ch, method, and properties mean?</p>