title: How do I use helper functions in Lumen?
body: <pre><code>    $credentials = app_path();
  </code></pre>
  
  <p>Results in:</p>
  
  <blockquote>
    <p>[Symfony\Component\Debug\Exception\FatalThrowableError]   Call to
    undefined function App\LtClasses\app_path()</p>
  </blockquote>
  
  <p>But it's listed as a helper here: <a href="https://laravel.com/docs/5.3/helpers#method-app-path" rel="noreferrer">https://laravel.com/docs/5.3/helpers#method-app-path</a></p>