 a descendant of `base`.
     */
    isDescendant: function(base, path) {
      //     path.startsWith(base + '.');
      return path.indexOf(base + '.') === 0;
    },

    /**
     * Replaces a previous base path with a new base path, preserving the
     * remainder of the path.
     *
     * User must ensure `path` has a prefix of `base`.
     *
     * Example:
     *
     * ```
     * Polymer.Path.translate('foo.bar', 'zot', 'foo.bar.baz') // 'zot.baz'
     * ```
     *
     * @memberof Polymer.Path
    