title: Fallback to default script if pretty url router could not fing a match
body: <p>I am implementing a pretty url router for my (php) application.
  Here is what I placed in .htaccess</p>
  
  <pre><code>RewriteEngine on
  RewriteRule (.+)? url_router.php
  </code></pre>
  
  <p>in url_router.php, I parse the requested url and see if a module has requested to capture the pretty url. If no match is made, I want to fetch the actual ur requested, for example,</p>
  
  <ul>
  <li>If the requested url is /core/admin.php and url_router.php doesn't recognize it as a pretty url for processing, I want the actual admin.php at /core/ to be executed.</li>
  <li>If the requested url is /blog/sample-post and I have a module blog which wants to take control. So now the content is served by the blog module.</li>
  </ul>
  
  <p>I have already implemented how the router calls other modules, but could not figure out how to fallback to default url when the router doesn't find a match</p>