title: Optional GET parameter in Express route
body: <p>The following:</p>
  
  <pre><code>app.get('/foo/start/:start/end/:end', blah.someFunc);
  </code></pre>
  
  <p>matches</p>
  
  <pre><code>/foo/start/1/end/4
  </code></pre>
  
  <p>but I want it to also match an optional parameter</p>
  
  <pre><code>/foo/start/1/end/4/optional/7
  </code></pre>
  
  <p>I've tried this:</p>
  
  <pre><code>app.get('/foo/start/:start/end/:end(/optional/:value)?', blah.someFunc);
  </code></pre>
  
  <p>but it doesn't match either of the above two examples.  I think it's because I'm trying to give it a <code>RegExp</code> when it's expecting something else?</p>
  
  <p>Thanks.</p>