code: public function setFormatter($formatter)
      {
          if ($formatter === null) {
              $formatter = new SerializeFormatter();
          }
  
          if (!$formatter instanceof FormatterInterface) {
              throw new Exception('Formatter must be an instance of Flintstone\Formatter\FormatterInterface');
          }
  
          $this->config['formatter'] = $formatter;
      }
docs: Set the formatter.
  
  @param FormatterInterface|null $formatter
  
  @throws Exception