code: public function setDownloader($type, DownloaderInterface $downloader)
      {
          $type = strtolower($type);
          $this->downloaders[$type] = $downloader;
  
          return $this;
      }
docs: Sets installer downloader for a specific installation type.
  
  @param  string              $type       installation type
  @param  DownloaderInterface $downloader downloader instance
  @return DownloadManager