module A = BetterSet (BatSet.Make(OrderedString)) (PprString);;
module B = BetterSet (Set.Make(OrderedString)) (PprString);;

# A.inter (A.of_list ["A"; "B"; "C"; "D"]) (A.of_list ["A"; "B"; "C"; "D"]);;
- : A.t = {}
# B.inter (B.of_list ["A"; "B"; "C"; "D"]) (B.of_list ["A"; "B"; "C"; "D"]);;
- : B.t = {A; B; C; D}