changeAttributes(ident uid, ident id, string title, string date, string time, string location) {
  assume exists /account[uid]/admin || exists /account[uid]/examiner[id];
 
  assume exists /exam[id]; # implicitly true in OO implementations
 
  update /exam[id]/title title;
  update /exam[id]/date date;
  update /exam[id]/time time;
  update /exam[id]/location location;
}