gistfile1.js

add: function (answer) {
    if (answer.has('order')) {
      return this;
    }
    var maxOrderModel = this.max(function (model) {
        return model.get('order');
    });
 
    if (_.isEmpty(maxOrderModel)) {
        answer.set('order', 0);
    } else {
        answer.set('order', maxOrderModel.get('order') + 1);
    }
    BB.Collection.prototype.add.apply(this, arguments);

    return this;
}