anchor.diff:          <textarea></textarea>
       </section>
   
  -    <section id="specs">
  -        <table>
  -            <thead>
  -                <tr>
  -                    <th>Input</th>
  -                    <th>Expected</th>
  -                    <th>Actual</th>
  -                </tr>
  -            </thead>
  -
  -            <tbody>
  -            </tbody>
  -        </table>
  -    </section>
  -
       <section id="docs">
           <iframe></iframe>
       </section>
  
positive.code: 
          function showingAST() {
            return astCheckBox.checked;
          }
  
          function showingSpecs() {
            return specsCheckBox.checked;
          }
  
          function showingDocs() {
  
negative.code:         var sections      = document.querySelectorAll('section'),
              checkboxes    = document.querySelectorAll('footer input[type="checkbox"]'),
              astCheckBox   = document.querySelector('input[name="ast"]'),
              docsCheckBox  = document.querySelector('input[name="docs"]');
  
          // The CodeMirror instance where we'll display the AST.
  