/**
  * @see sfValidatorBase
  */
 protected function doClean($value)
 {
     $clean = (string) $value;
     if (!$this->getOption('separator')) {
         $clean = str_replace('-', '', $clean);
     }
     if (!Validate_PL::nip($clean)) {
         throw new sfValidatorError($this, 'invalid');
     }
     return $clean;
 }