bp_notifications_clear_all_for_user_cache_before_delete( int $args )

function bp_notifications_clear_all_for_user_cache_before_delete( $args ) {

	// Pull up a list of items matching the args (those about te be deleted).
	$ns = BP_Notifications_Notification::get( $args );

	$user_ids = array();
	foreach ( $ns as $n ) {
		$user_ids[] = $n->user_id;
	}

	$user_ids = array_unique( $user_ids );
	foreach ( $user_ids as $user_id ) {
		bp_notifications_clear_all_for_user_cache( $user_id );
	}
}