type 'a iter = ('a -> unit) -> unittype 'a printer = Stdlib.Format.formatter -> 'a -> unitmodule type OrderedType = Stdlib.Map.OrderedTypemodule type S = sig ... endmodule Make
  (O : Stdlib.Map.OrderedType) : 
  S with type 'a t = 'a Stdlib.Map.Make(O).t and type key = O.t