1:- use_module(library(pita)).    2
    3:- if(current_predicate(use_rendering/1)).    4:- use_rendering(c3).    5:- endif.    6
    7:- pita.    8
    9:- begin_lpad.   10
   11sampled_male(X):0.5:-
   12  db(male(X)).
   13
   14:- end_lpad.   15
   16male(john).
   17male(david).
   18
   19female(anna).
   20female(elen).
   21female(cathy).

?- prob(sampled_male(X),Prob). % expected result 0.5 for X=john, X=david

*/