public function reverseTransform($value)
 {
     if ('' === $value || null === $value) {
         return null;
     }
     if (!is_string($value)) {
         return null;
     }
     $dateRange = new DateRange($this->date_format, $this->daterange_separator);
     $dateRange->parseData($value);
     return $dateRange;
 }