change_arg/3 = nb_linkarg/3 ? (Was: PIPs from the Basilisk Chamber)

I came up with a findall/3 for SWI-Prolog that
doesn’t use call_cleanup/2. The findall2/3 realization
uses nb_linkarg/3 and duplicate_term/2.
findall2(Template, Goal, List) :-
    sys_find2_init(State),
    (Goal, sys_find2_next(Template, State), fail; true),
    sys_find2_fini(State, List).
sys_find2_init(X) :-
    X = v(_,_),
    C = [-|_],
    nb_linkarg(1, X, C),
    nb_linkarg(2, X, C).
sys_find2_next(T, X) :-
    C = [_|_],
    duplicate_term(T, H),
    nb_linkarg(1, C, H),
    arg(1, X, J),              %%% known end cell
    nb_linkarg(2, J, C),
    nb_linkarg(1, X, C).
sys_find2_fini(v(C,D), L) :-
    nb_linkarg(2, C, []),
    arg(2, D, L).
Its not as fast as the bundled findall/3.