title: file_exists() or is_readable()
body: <p>Which one should you use when you want to include a PHP file?</p>
  
  <pre><code>if(file_exists($file) require "$file";
  </code></pre>
  
  <p>or</p>
  
  <pre><code>if(is_readable($file) require "$file";
  </code></pre>
  
  <p>?</p>