code: func renderImage(renderedACI acirenderer.RenderedACI, dir string, ap acirenderer.ACIProvider, uidRange *user.UidRange) error {
  	for _, ra := range renderedACI {
  		rs, err := ap.ReadStream(ra.Key)
  		if err != nil {
  			return err
  		}
  
  		// Overwrite is not needed. If a file needs to be overwritten then the renderedACI builder has a bug
  		if err := ptar.ExtractTar(rs, dir, false, uidRange, ra.FileMap); err != nil {
  			rs.Close()
  			return errwrap.Wrap(errors.New("error extracting ACI"), err)
  		}
  		rs.Close()
  	}
  
  	return nil
  }
docs: // Given a RenderedACI, it will extract, under the provided directory, the
  // needed files from the right source ACI.
  // The manifest will be extracted from the upper ACI.
  // No file overwriting is done as it should usually be called
  // providing an empty directory.