Configure application instance.

    Args:
        app (Flask): initialized Flask app instance
        config (Optional[path]): path to a Python module config file
        config_obj (Optional[class]): Python config object

def configure_app(app, config=None, config_obj=None):
    """Configure application instance.

    Args:
        app (Flask): initialized Flask app instance
        config (Optional[path]): path to a Python module config file
        config_obj (Optional[class]): Python config object
    """
    app.config.from_object(config_obj or BaseConfig)
    if config is not None:
        app.config.from_pyfile(config)