Basic flask app factory pattern

main.py

def create_app():
    """                                                                                                                                                
    Create Flask application using the app factory pattern.                                                                                            
                                                                                                                                                       
    :return: Flask app                                                                                                                                 
    """

    app = Flask(__name__, instance_relative_config=True)

    app.config.from_object('config.settings')
    app.config.from_pyfile('settings.py', silent=True)

    @app.route('/')
    def index():
        """                                                                                                                                            
        Render a Hello World response.                                                                                                                 
                                                                                                                                                       
        :return: Flask response                                                                                                                        
        """

        return 'Hello World!'

    return app