public function __construct($str)
 {
     $this->response = new \SAML2_Response(XMLConverter::str_to_xml($str));
 }
 public static function modify_response($original_response_str, array $values)
 {
     $original_response = new \SAML2_Response(XMLConverter::str_to_xml($original_response_str));
     $modified_response = self::combine_response($values, $original_response);
     return self::to_str($modified_response, $values);
 }