Future<void> main() async {
 /// get username and password from the environment-variables
 final env = Platform.environment;
 final username = env['IG_USERNAME'];
 final password = env['IG_PASSWORD'];

 final StateStorage storage = /* create the storage */;
 final InstaClient ig = InstaClient();
 /// this will ensure, the state is saved after each request
 ig.request.httpClient.interceptors.add(
     ResponseInterceptor(ig, (json) => storage.saveState(jsonEncode(json))));

 if (!await storage.exists()) {
   /// generate default values for the state
   ig.state.init();
   await storage.createState();
   await ig.account.login(username, password);
 } else {
   /// load the state, and you're good to go
   ig.state = InstaState.fromJson(jsonDecode(await storage.loadState()));
 }

 print('logged in!');
}

/// An example state-storage
mixin StateStorage {
 FutureOr<bool> exists();

 FutureOr<void> createState();

 FutureOr<String> loadState();

 FutureOr<void> saveState(String encodedState);
}