title: django - show the length of a queryset in a template
body: <p>In my html file, how can I output the size of the queryset that I am using (for my debugging purposes)</p>
  
  <p>I've tried</p>
  
  <pre><code>{{ len(some_queryset) }}
  </code></pre>
  
  <p>but that didn't work. What is the format?</p>