/**
  * Return standard error message
  *
  * @return void
  */
 public function __construct()
 {
     parent::__construct('this method cannot be called before phpCAS::client() or phpCAS::proxy()');
 }
 /**
  * Return standard error meessage
  *
  * @return void
  */
 public function __construct()
 {
     parent::__construct('An authentication call hasn\'t happened yet.');
 }