code: function (id, done, headers, config) {
          if (!_.isNumber(parseInt(id, 10))) {
            return done(new Error('id must be specified.'));
          }
          this._request(['folders', id], 'GET', done, null, null, null, headers, null, config);
        }
docs: Retrieves the full metadata about a folder,
  including information about when it was last updated as well as the files and folders
  contained in it. The root folder of a Box account is always represented by the id “0″.
  @summary Get Information About a Folder.
  @see {@link https://developers.box.com/docs/#folders-get-information-about-a-folder}
  @param {number} id - The folder's ID.
  @param {requestCallback} done - The callback to invoke (with possible errors) when the request returns.
  @param {?RequestHeaders} [headers] - Additional headers.
  @param {?RequestConfig} [config] - Configure the request behaviour.