test_gen(N) :-
    abolish(currentnum,2),
    get_seconds(T1),
    t_gen(N),
    get_seconds(T2),
    T3 is T2 - T1,
    write(T3), write(' seconds.'), nl.

t_gen(0) :-
    !.
t_gen(N) :-
    gensym(x,_),
    M is N - 1,
    t_gen(M),
    !.
   
