WordPress at a glance
function is not described

privacy_ping_filter() WP 2.1.0

Check whether blog is public before returning sites.

No Hooks.

Return

Mixed. Empty string if blog is not public, returns $sites, if site is public.

Usage

privacy_ping_filter( $sites );
$sites(mixed) (required)
Will return if blog is public, will not return if not public.

Code of privacy ping filter: wp-includes/comment.php WP 5.2.1

<?php
function privacy_ping_filter( $sites ) {
	if ( '0' != get_option( 'blog_public' ) ) {
		return $sites;
	} else {
		return '';
	}
}