gistfile1.js

var Photo, Photos, Album, Albums;

Photo = Y.Base.create('photo', Y.Model, [], {}, {
    ATTRS: {
        imgUrl: {},

        caption: {}
    }
});

Photos = Y.Base.create('photos', Y.ModelList, [], {model: Photo});

Album = Y.Base.create('album', Y.Model, [], {
    initializer: function () {
        this._photos = new Y.Photos();
    },

    _getPhotos: function () {
        return this._photos;
    },

    _setPhotos: function (photos) {
        return this._photos.reset(photos);
    }
}, {
    ATTRS: {
        name: {},

        photos: {
            getter   : '_getPhotos',
            setter   : '_setPhotos',
            validator: Y.Lang.isArray
        }
    }
});

Albums = Y.Base.create('albums', Y.ModelList, [], {model: Album});