in example/main.dart [75:86]
void main() async {
var client = await createClient();
// Once you have a Client, you can use it just like any other HTTP client.
print(await client.read(Uri.http('example.com', 'protected-resources.txt')));
// Once we're done with the client, save the credentials file. This ensures
// that if the credentials were automatically refreshed while using the
// client, the new credentials are available for the next run of the
// program.
await credentialsFile.writeAsString(client.credentials.toJson());
}