gistfile1.js

		Object.defineProperty(instance, key, {
			get: function () {
				return opts.data[key];
			},
			set: function (val) {
				if (Model.allProperties[key].key === true && opts.data[key] != null) {
					return;
				}

				if (!setInstanceProperty(key, val)) {
					return;
				}

				if (opts.autoSave) {
					saveInstanceProperty(key, val);
				} else if (opts.changes.indexOf(key) === -1) {
					opts.changes.push(key);
				}
			},
			enumerable: true
		});