title: How do I make dynamic ids in Haml?
body: <pre><code>#item
  </code></pre>
  
  <p>creates a div with id="item"</p>
  
  <pre><code>.box#item
  </code></pre>
  
  <p>creates a div with class="box" and id="item"</p>
  
  <pre><code>.box#="item "+x
  </code></pre>
  
  <p>creates a div with class="box" and a comment '#="item"+x'</p>
  
  <pre><code>.box#
    ="item"+x
  </code></pre>
  
  <p>throws "Illegal element: classes and ids must have values."</p>
  
  <p>How do I get set the id to a variable?</p>