type 'a mapping = 'a inout arrayand 'a inout = {in_env : 'a env;out_env : 'a env;
}val empty_inout : unit -> 'a inoutval new_node_array : F.flow -> 'a -> 'a arrayval varmap_union : ('a -> 'a -> 'a) -> 'a env -> 'a env -> 'a envval varmap_diff :
('a -> 'a -> 'a) ->
('a -> bool) ->
'a env ->
'a env ->
'a envval display_mapping : F.flow -> 'a mapping -> ('a -> string) -> unit