let add_dpd_in_g graph v1 dpd_kind part_opt v2 =
(* let part_opt = match part_opt with Some _ | None -> None in *)
P.debug ~level:2 "add_dpd : %a -> %a@."
Macros.pretty_node v1
Macros.pretty_node v2;
G.add_dpd graph v1 dpd_kind part_opt v2