code: public function getDownloader($type)
      {
          $type = strtolower($type);
          if (!isset($this->downloaders[$type])) {
              throw new \InvalidArgumentException(sprintf('Unknown downloader type: %s. Available types: %s.', $type, implode(', ', array_keys($this->downloaders))));
          }
  
          return $this->downloaders[$type];
      }
docs: Returns downloader for a specific installation type.
  
  @param  string                    $type installation type
  @throws \InvalidArgumentException if downloader for provided type is not registered
  @return DownloaderInterface