public function getGravatarUrl(
        $size = 80,
        $defaultImage = 'mm',
        $rating = 'g',
        array $attributes = []
    ) {
        $params = http_build_query([
            's' => $size,
            'd' => $defaultImage,
            'r' => $rating,
        ] + $attributes);

        return $this->getGravatarDefaultUrl() . '?' . $params;
    }