code: public function getReservedCodes()
      {
          $reserved = [];
  
          /** @var ErrorFactoryInterface|string $factory */
          foreach ($this->factories as $factoryClass => $factory) {
              $reserved[$factoryClass] = $factory->getReservedDiapason();
          }
  
          return $reserved;
      }
docs: Get reserved codes
  
  @return array