title: How to use file system function 'exists' in symfony2?
body: <p>I checked symfony2 API docs <a href="http://api.symfony.com/2.1/index.html" rel="nofollow">here</a>,</p>
  
  <p>Few File system functions are available in Symfony\Component\Filesystem\Filesystem  </p>
  
  <p>i used '<strong>mkdir</strong>' and it worked fine but, unable to use '<strong>exists</strong>' function  </p>
  
  <p>public Boolean exists(string|array|Traversable $files)  </p>
  
  <p>It gives error </p>
  
  <pre><code>Fatal error: Call to undefined function Survey\BlogBundle\Controller\exists()
  </code></pre>