nsole.log("Result: "+ result + " (should be 10)");
        }

        class Storage {
            constructor(databaseName) {
                this._databaseName = databaseName;
                this._database = null;
            }

            open() {
                const req = window.indexedDB.open(this._databaseName);
                const self = this;
                req.onupgradeneeded = function(ev) {
                    const db = ev.target.result;
                    const oldVersion = ev.oldVersion