code: function () {
      var items = Array.prototype.slice.call(arguments);
      this.source.push.apply(this.source, items);
      this._updateInfo();
  
      // DEPRECATED
      this.emit("insert", items[0], this.length - 1);
      this.emit("update", { insert: items, index: this.length - 1});
    }
docs: Pushes an item onto the collection
  @method push
  @param {Object} item