code: func (cli *Client) ImageSave(ctx context.Context, imageIDs []string) (io.ReadCloser, error) {
  	query := url.Values{
  		"names": imageIDs,
  	}
  
  	resp, err := cli.get(ctx, "/images/get", query, nil)
  	if err != nil {
  		return nil, err
  	}
  	return resp.body, nil
  }
docs: // ImageSave retrieves one or more images from the docker host as an io.ReadCloser.
  // It's up to the caller to store the images and close the stream.