let fold_topset_ok f m acc =
match m with
Top(Top_Param.Set t, _) ->
let acc = if Null_Behavior.zone then acc else f K.null V.top acc in
Top_Param.O.fold
(fun x acc -> f x V.top acc)
t
acc
| Top(Top_Param.Top, _) ->
raise Error_Top
| Map m ->
M.fold f m acc