bbp_bump_forum_topic_count_hidden( int $forum_id, int $difference = 1 )

function bbp_bump_forum_topic_count_hidden( $forum_id = 0, $difference = 1 ) {

	// Get some counts
	$forum_id    = bbp_get_forum_id( $forum_id );
	$topic_count = bbp_get_forum_topic_count_hidden( $forum_id, true );
	$new_count   = (int) $topic_count + (int) $difference;

	// Update this forum id
	update_post_meta( $forum_id, '_bbp_topic_count_hidden', (int) $new_count );

	return (int) apply_filters( 'bbp_bump_forum_topic_count_hidden', (int) $new_count, $forum_id, (int) $difference );
}