:- checked calls qsort(A,B)
   : list_num(A).

:- checked success qsort(A,B)
   => list_num(B).

:- check comp partition(_A,_B,_C,_D)
   + not_fails.

:- checked calls partition(A,B,C,D)
   : ( ground(A), num(B) ).

:- checked success partition(A,B,C,D)
   => ( list(num,C), ground(D) ).

:- checked comp partition(_A,_B,_C,_D)
   + is_det.

