title: Using python code in pyjade
body: <p>I'm trying to generate a list using pyjade, like so:</p>
  
  <pre><code>ul
    - for i, (label, link) in enumerate(tabs)
      li(class="selected" if i == selected_index else "")
        a(href=link)= label
  </code></pre>
  
  <p>But I see this error:</p>
  
  <blockquote>
    <p>UndefinedError: 'enumerate' is undefined</p>
  </blockquote>
  
  <p>I must be embedding python code into Jade wrong.  What's the right way to do this?</p>