if (defined (x) || defined(y) || defined(z) {
        for ($i = 1; $i<=$max_x ; $i++) {
          $router cmd ( set interface ge-3/1/0.$i )
          if ($i == $max_x) {
              break;
          }
           if (defined(y) {
           for ($i = $max_x+1; $i<=$max_y ; $i++) {
           $router cmd ( set interface ge-3/1/0.$i )
         if ($i == $max_y) {
              break;
          }             
}}