code: func ArchiveFormValues(r *http.Request, vars map[string]string) (ArchiveOptions, error) {
  	if err := ParseForm(r); err != nil {
  		return ArchiveOptions{}, err
  	}
  
  	name := vars["name"]
  	if name == "" {
  		return ArchiveOptions{}, badParameterError{"name"}
  	}
  	path := r.Form.Get("path")
  	if path == "" {
  		return ArchiveOptions{}, badParameterError{"path"}
  	}
  	return ArchiveOptions{name, path}, nil
  }
docs: // ArchiveFormValues parses form values and turns them into ArchiveOptions.
  // It fails if the archive name and path are not in the request.