title: Create dynamic URLs in Flask with url_for()
body: <p>Half of my Flask routes requires a variable say, <code>/&lt;variable&gt;/add</code> or <code>/&lt;variable&gt;/remove</code>. How do I create links to those locations?</p>
  
  <p><code>url_for()</code> takes one argument for the function to route to but I can't add arguments?</p>