Biocaml 0.4-dev : Biocaml_genomeMap.Make.Selection.inter

let inter u v =

   Map.fold u ~init:Map.empty ~f:(fun ~key:k ~data:set_u accu ->

     match Map.find v k with

     | Some set_v -> Map.add accu ~key:k ~data:(Biocaml_iset.inter set_u set_v)

     | None -> accu

    )