let get_test_edges g v =
match CFG.succ_e g v with
| [e1; e2] ->
begin match !(CFG.E.label e1), !(CFG.E.label e2) with
| (Ethen|EbackThen), (Eelse|EbackElse) -> e1, e2
| (Eelse|EbackElse), (Ethen|EbackThen) -> e2, e1
| _ -> failwith ("[cfg] test node with invalid edges")
end
| _ -> raise (Invalid_argument "[cfg:get_test_edges] not a test")