title: Force location to have same pattern
body: <p>I was wondering if it's possible to force location only accept when the route has pattern <code>[a-z]+:[a-z]+</code>. Example: <code>/events/prefix:sufix</code></p>
  
  <p>I've tried to reach it using:</p>
  
  <pre><code>    location ~ /events/([a-z]+:[a-z]+)$ {...}
  </code></pre>
  
  <p>Also, I would like to avoid stuff like <code>/events/prefix:sufix/more/more</code>. Is possible?</p>
  
  <p>But it didn't work.</p>
  
  <p>What's the proper way to set it?</p>