private static async Task<UserCredential> AuthorizeAsyncCore(
            GoogleAuthorizationCodeFlow.Initializer initializer, IEnumerable<string> scopes, string user,
            CancellationToken taskCancellationToken, IDataStore dataStore = null)
        {
            initializer.Scopes = scopes;
            initializer.DataStore = dataStore ?? new FileDataStore(Folder);
            var flow = new GCSMAuthorizationCodeFlow(initializer,user);

            // Create an authorization code installed app instance and authorize the user.
            return await new AuthorizationCodeInstalledApp(flow, new LocalServerCodeReceiver()).AuthorizeAsync
                (user, taskCancellationToken).ConfigureAwait(false);
        }