/**
  * Retrieves all saved tokens.
  *
  * @return array<array>
  *		 the saved tokens as, will be empty if no tokens have been saved
  */
 protected function retrieveTokens()
 {
     $tokens = $this->backendUser->getSessionData('formTokens');
     if (!is_array($tokens)) {
         $tokens = array();
     }
     return $tokens;
 }