D5 Business Line

Last function on function.php says

add_filter('the_title', 'd5businessline_title');
	function d5businessline_title($title) {
        if ( '' == $title ) {
            return '(Untitled)';
        } else {
            return $title;
        }
    }

i’m not sure is it correct place for add_filter('the_title', 'd5businessline_title');
in this filter?
when i try to add some custom function it breaks website.
Maybe that is the problem after updating that makes screen go white 🙂