private function isGoodHttpReferer(Sanitizer $sanitizer)
 {
     //Sanitize an extra scalar value inside of INPUT_SERVER.
     $sanitizer->httpRefererExists();
     $sanitizer->httpRefererHasGoodSize();
     $sanitizer->setExtInputElement('HTTP_REFERER');
     $sanitizer->sanitizeElement();
     //Validate the extra scalar value from INPUT_SERVER.
     $this->setFilteredExtElement($sanitizer->getFilteredExtElement());
     return $this->validateFilteredElement();
 }