code: function (options) {
      var regions;
      this._initRegionManager();
  
      if (_.isFunction(this.regions)) {
        regions = this.regions(options);
      } else {
        regions = this.regions || {};
      }
  
      this.addRegions(regions);
    }
docs: Internal method to initialize the regions that have been defined in a `regions` attribute on this layout.