title: Get lengths of a list in a jinja2 template
body: <p>How do I get the number of elements in a list in jinja2 template?</p>
  
  <p>For example, in Python:</p>
  
  <pre><code>print(template.render(products=[???]))
  </code></pre>
  
  <p>and in jinja2</p>
  
  <pre><code>&lt;span&gt;You have {{what goes here?}} products&lt;/span&gt;
  </code></pre>