I had a small code that I wrote for the program I don't know if you want to use it or not. its a very small code not a big one.
small(X) :- X < 50.
medium(X) :- X >= 50, X =< 100.
big(X) :- X > 100.
% classify(+N, ?Classification)
classify(N, small) :- ...guard...test N for smallness...
classify(N, medium) :- ...guard...test N for mediumness...
classify(N, big) :- ...guard...test N for bigness...
classify(N, small) :- must_be(number,N), N < 50, !.
classify(N, medium) :- must_be(number,N), N >= 50, N =< 100, !.
classify(N, big) :- must_be(number,N), N > 100.