/**
  * @return void
  */
 protected function getChecker()
 {
     $difference = MediDateTime::differenceUntilNow($this->checker);
     if ($difference > $this->checking_duration) {
         // auction must close
         while (!$this->closed()) {
             $this->close();
         }
         return 'Auction closed!';
     } else {
         return 'Checking...';
     }
 }
 private function getCheckingResponse()
 {
     $difference = MediDateTime::differenceUntilNow($this->timer_start);
     if ($difference >= $this->checking_duration) {
         // auction is done checking and must be closed
         $this->closeAuction();
         return self::AUCTION_STATUS_MESSAGE_CLOSED;
     }
     return self::AUCTION_STATUS_MESSAGE_CHECKING;
 }