Fonksiyonu:

 /**
 * Retrieve post title.
 *
 * If the post is protected and the visitor is not an admin, then "Protected"
 * will be displayed before the post title. If the post is private, then
 * "Private" will be located before the post title.
 *
 * @since 0.71
 *
 * @param int $id Optional. Post ID.
 * @return string
 */

function get_the_title( $id = 0 ) {
    $post = &get_post($id);

$title = isset($post->post_title) ? $post->post_title : '';
$id = isset($post->ID) ? $post->ID : (int) $id;

if ( !is_admin() ) {
    if ( !empty($post->post_password) ) {
        $protected_title_format = apply_filters('protected_title_format', __('Protected: %s'));
        $title = sprintf($protected_title_format, $title);
    } else if ( isset($post->post_status) && 'private' == $post->post_status ) {
        $private_title_format = apply_filters('private_title_format', __('Private: %s'));
        $title = sprintf($private_title_format, $title);
    }
}
return apply_filters( 'the_title', $title, $id );
}

Ben parametre __('Protected: %s') altında belirli bir kod satırında ne demek anlamıyorum. Bu parametrenin ne tür?

$protected_title_format = apply_filters('protected_title_format', __('Protected: %s'));