code: protected function initHandler(HandlerInterface $handler)
      {
          if ($this->formatter != null) {
              $handler->setFormatter($this->formatter);
          }
  
          foreach ($this->processors as $processor) {
              $handler->pushProcessor($processor);
          }
  
          return $handler;
      }
docs: Sets formatter and processors.
  
  @param HandlerInterface $handler
  @return HandlerInterface