+let uri_list_diff l2 l1 =
+ let module S = UriManager.UriSet in
+ let s1 = List.fold_left (fun set uri -> S.add uri set) S.empty l1 in
+ let s2 = List.fold_left (fun set uri -> S.add uri set) S.empty l2 in
+ let diff = S.diff s2 s1 in
+ S.fold (fun uri uris -> uri :: uris) diff []
+