code: function () {
  
      var items = Array.prototype.slice.call(arguments);
      this.source.unshift.apply(this.source, items);
      this._updateInfo();
  
      // DEPRECATED
      this.emit("insert", items[0], 0);
      this.emit("update", { insert: items });
    }
docs: Unshifts an item onto the collection
  @method unshift
  @param {Object} item