_defaults(route) {
        return route.parameterSegments
            .filter(({ name }) => this._config.defaults[name])
            .reduce(
                (result, { name }, i) => ({ ...result, [name]: this._config.defaults[name] }),
                {},
            );
    }
Populate default parameters for the given route.

@example
// with default parameters { locale: 'en', country: 'US' } and 'posts.show' route '{locale}/posts/{post}'
defaults(...); // { locale: 'en' }

@param {Route} route
@return {Object} Default route parameters.