from flask import Flask, render_template from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user app = Flask(__name__) app.secret_key = 'secret_key' login_manager = LoginManager() login_manager.init_app(app) # Define a user model class User(UserMixin): pass # Define an anonymous user login_manager.anonymous_user = User # Load a user with id @login_manager.user_loader def load_user(user_id): # return a user object return User() # Login route @app.route('/login') def login(): user = User() # log the user in login_user(user) return 'Logged in!' # Logout route @app.route('/logout') @login_required def logout(): # log the user out logout_user() return 'Logged out!' # Protected route @app.route('/protected') @login_required def protected(): return 'This is a protected page. Logged in as ' + current_user.get_id() if __name__ == '__main__': app.run()In this example, we define a user model that inherits from UserMixin, which provides basic methods required for user authentication. We also define an anonymous user by assigning a User object to the anonymous_user attribute of the LoginManager class. The `load_user` function is used to load a user by their user id. In this example, we simply return a new User object. The `login` and `logout` routes demonstrate how to log a user in and out using the login_user and logout_user functions provided by flask_login. The `protected` route is a protected page that can only be accessed by authenticated users, which is enforced using the login_required decorator. Package: flask_login (library)