Make backbone.js friendly for use with async.js

gistfile1.js

//Note, works with either Backbone.Model or Backbone.Collection
//Returns a function that will fetch the provided model and works with
//async's callback API
function asyncFetch(model) {
    return function (callback) {
        model.fetch({
            success: function (model) {callback(null, model);},
            error: function (model, response) {callback(response);}
        });
    };
}

//Returns a function that will save the provided model and works with
//async's callback API
function asyncSave(model) {
    return function (callback) {
        model.save(null, {
            success: function (model) {callback(null, model);},
            error: function (model, response) {callback(response);}
        });
    };
}

//Example usage
async.parallel([asyncSave(model1), asyncSave(model2), asyncFetch(someCollection)],
    function (error) {
        if (error) {
            return self.displayError(error);
        }
        self.displaySuccess("Done!");
    }
);