def before_init_app(self, app: FlaskUnchained):
        """
        Configure the Jinja environment and template loader.
        """
        from .templates import (UnchainedJinjaEnvironment,
                                UnchainedJinjaLoader)
        app.jinja_environment = UnchainedJinjaEnvironment
        app.jinja_options = {**app.jinja_options,
                             'loader': UnchainedJinjaLoader(app)}
        app.jinja_env.globals['url_for'] = url_for

        for name in ['string', 'str']:
            app.url_map.converters[name] = StringConverter
Configure the Jinja environment and template loader.