docs: function (prop) {
        var keys = Object.keys(this.keyMap);
        var items = this.items.map(function (item, i) {
          item.key = keys[i];
          return item;
        });
        var sorted = lazy.arraySort(items, prop);
        this.items = sorted;
        this.keyMap = this.items.reduce(function (acc, item, i) {
          acc[item.key] = i;
          return acc;
        }, {});
        return this;
      }