:- import get_returns_for_call/2 from tables.

test :- a, fail.
test :-
	( a -> writeln('a is true') ; writeln('a is false') ),
	( c -> writeln('c is true') ; writeln('c is false') ),
	( d -> writeln('d is true') ; writeln('d is false') ),
	( ob -> writeln('ob is true') ; writeln('ob is false') ), fail.
test :- get_returns_for_call(b(_), Return),
	write(Return), writeln(' is true'), fail.
test.

%--------------------------------------------------------------

:- table a/0, ob/0, b/1, c/0, d/0, e/1.

a :- ob, d.

ob :- b(_).

b(X) :- c, e(X).
b(1).

c :- tnot(a).

d :- fail.

e(2).