code: function(name, options) {
          if (this._loader.modules[name]) {
            doEnsureEvaluated(this._loader.modules[name], [], this._loader);
            return Promise.resolve(this._loader.modules[name].module);
          }
          return importPromises[name] || createImportPromise(name, loadModule(this._loader, name, {}));
        }
docs: 26.3.3.9 keys not implemented 26.3.3.10