let print_group_xml (gl:student list) (groupnum:int) =
let thislist = select (fun s -> s.group == groupnum) gl in
let studnode = Xml.Element ("students", [], List.map (student_to_xml) thislist) in
let projnode = Xml.Element ("projects", [], List.map (project_to_xml)
(List.sort (fun u v -> compare u.add v.add) (get_group_projects groupnum))) in
Xml.Element ("group",[("number",(string_of_int groupnum)); ("name",(get_group_name groupnum))],
([projnode;studnode]))