code: public static function registerWriter($writerType, $writerClass)
      {
          if (!is_a($writerClass, Writer\IWriter::class, true)) {
              throw new Writer\Exception('Registered writers must implement ' . Writer\IWriter::class);
          }
  
          self::$writers[$writerType] = $writerClass;
      }
docs: Register a writer with its type and class name.
  
  @param string $writerType
  @param string $writerClass