code: function coerceRoot(root) {
    var coerced = root.substring().trim();
    var len = coerced.length;
    if (len > 0 && coerced[len - 1] !== '/') {
      coerced = coerced + '/';
    }
    return coerced;
  }
docs: Trim a root and add tailing slash if not exists.
  @param {String} root A root.
  @returns {String} The coerced root.
  @private