lected) {
        var item = this.items[index];
        if (item) {
          return this._valueForItem(item);
        }
      } else {
        return index;
      }
    },

    _valueForItem: function(item) {
      var propValue = item[Polymer.CaseMap.dashToCamelCase(this.attrForSelected)];
      return propValue != undefined ? propValue : item.getAttribute(this.attrForSelected);
    },

    _applySelection: function(item, isSelected) {
      if (this.selectedClass) {
        this.toggleClass(this.selected