protected static function getWorldContries($only_names = false) : Collection
    {
        $file = __DIR__ . "/../Assets/topojson/world-countries.json";

        return Collection::make(
            json_decode(file_get_contents($file), true)['objects']['countries1']['geometries']
        )->map(function ($country) use ($only_names) {
            if ($only_names) {
                return $country['properties']['name'];
            }
            return $country['properties'];
        });
    }