/**
  * Initially processes $_FILES superglobal for easier use.
  * Only for internal usage.
  */
 protected static function prefetchFiles()
 {
     self::$_files = array();
     if (!isset($_FILES) || !is_array($_FILES)) {
         return;
     }
     foreach ($_FILES as $class => $info) {
         self::collectFilesRecursive($class, $info['name'], $info['tmp_name'], $info['type'], $info['size'], $info['error']);
     }
 }