title: PHP Slim-3: How to redirect internally to another route
body: <p>I have a generic route like below - </p>
  
  <pre><code>$app-&gt;map(['GET', 'POST'], "/", function (\Slim\Http\Request $request, \Slim\Http\Response $response) use ($app) {
      // Some random version 1 processing here ...
  }
  </code></pre>
  
  <p>And I have a v2 version of the same like below - </p>
  
  <pre><code>$app-&gt;map(['GET', 'POST'], "/api/v2", function (\Slim\Http\Request $request, \Slim\Http\Response $response) use ($app) {
      // Some random version 2 processing here ...
  }
  </code></pre>
  
  <p>I have a problem to solve - </p>
  
  <p><em>The frontend always hits the v1 of the API (the generic route). I need to internally redirect to v2, based on the parameter <code>appversion</code>'s value.</em></p>
  
  <p>How can I do this in slim framework routing without issuing 302 redirect headers back to the client? Basically, I need to redirect internally to the server itself. </p>
  
  <p><strong>Note:</strong> I am aware of Nginx and Apache rewrites. Let us keep them aside and limit the scope to slim framework routing alone.</p>