Как правильно обвернуть php в тег span?

function main_categories($id, $separator=" - ") {

    global $cat_info;

    if( !$id ) return;

    $parent_id = $cat_info[$id]['parentid'];

    $list = $cat_info[$id]['name'];

    while ( $parent_id ) {
        $list = $cat_info[$parent_id]['name'] . "{$separator} " . $list;

        $parent_id = $cat_info[$parent_id]['parentid'];

        if( $parent_id ) {
            if( $cat_info[$parent_id]['parentid'] == $cat_info[$parent_id]['id'] ) break;
        }

    }

    return $list;
}