declare option saxon:output "indent=yes";

<result xmlns:pets="http://www.fi.muni.cz/~bar/pets"
 xmlns:devs="http://www.fi.muni.cz/~bar/devices">
 <pets>
 {
    for $pet in //pets:pet
    return
      $pet
 }
 <total-price>
    {
        sum(//pets:price)
    }
 </total-price>
 </pets>
 <devices>
  {
    for $device in //devs:device
    return 
      $device
  }
  <total-price>
    {
	sum(//devs:price)
    }
  </total-price>
 </devices>
</result>