cessType], [threadType], [railStage, initiatorType]]
   *
   * The returned string is of the form
   *   "$processtype:$threadType:$railStage:$initiatorType".
   *
   * @param {Array.<!Array.<string>>} path
   * @returns {string}
   */
  function stringifyPathName_(path) {
    const decodedPath = decodePath_(path);
    return [
      decodedPath.processType,
      decodedPath.threadType,
      decodedPath.railStage,
      decodedPath.initiatorType
    ].join(':');
  }

  /**
   * This class is used to trave