code: public static function createReader($readerType)
      {
          if (!isset(self::$readers[$readerType])) {
              throw new Reader\Exception("No reader found for type $readerType");
          }
  
          // Instantiate reader
          $className = self::$readers[$readerType];
          $reader = new $className();
  
          return $reader;
      }
docs: Create Reader\IReader.
  
  @param string $readerType Example: Xlsx
  
  @throws Reader\Exception
  
  @return Reader\IReader