/**
  * instance method
  *
  * Get singleton instance of `Ai1ec_Loader`.
  *
  * @return Ai1ec_Loader Cached self instance
  */
 public static function instance()
 {
     if (!self::$_instance instanceof Ai1ec_Loader) {
         self::$_instance = new Ai1ec_Loader();
     }
     return self::$_instance;
 }
 /**
  * Get a list of OAuth providers
  *
  * @return array Map of provider names and corresponding classes
  *
  * @staticvar $names Map of provider names and corresponding classes
  */
 protected function _get_providers()
 {
     static $names = NULL;
     if (NULL === $names) {
         $classes = Ai1ec_Loader::instance()->get_matches('/^Ai1ec_Oauth_Provider_[A-Z][a-z]+$/');
         $names = array();
         foreach ($classes as $class) {
             $names[$this->_normalize_name($class)] = $class;
         }
     }
     return $names;
 }