function spi_show_gravatar_in_author_bio($content) {
    error_log("spi_show_gravatar_in_author_bio triggered");
    if (is_author()) {
        $author_id = get_the_author_meta('ID');
        error_log("Author ID: " . $author_id);
        $avatar = get_avatar($author_id, 100, '', 'Avatar autore');
        error_log("Avatar HTML: " . $avatar);
        return $avatar . $content;
    }
    return $content;
}