define ncsubseq(l);
    lvars acc = [], gap_started = false, is_continuous = true;
    define do_it(l1, l2);
        dlocal gap_started;
        lvars el, save_is_continuous = is_continuous;
        if l2 = [] then
            if not(is_continuous) then
                cons(l1, acc) -> acc;
            endif;
        else
            front(l2) -> el;
            back(l2) -> l2;
            not(gap_started) and is_continuous -> is_continuous;
            do_it(cons(el, l1), l2);
            save_is_continuous -> is_continuous;
            not(l1 = []) or gap_started -> gap_started;
            do_it(l1, l2);
        endif;
    enddefine;
    do_it([], rev(l));
    acc;
enddefine;

ncsubseq([1 2 3 4 5]) =>