true.

?- cool(arcata).
true.

?- cool(houston).
false.

?- cool(refrigerator).
false.

?- cool(Where).
Where = arcata.

?- Where.
% ... 1,000,000 ............ 10,000,000 years later
% 
%       >> 42 << (last release gives the question)
?- cool(George).
George = arcata.

?- cool(X), mother_of(Y, Z).
X = arcata,
Y = thomas,
Z = sharon ;;
X = arcata,
Y = terry,
Z = sharon.

?- mother_of(Person1, Person2).
Person1 = thomas,
Person2 = sharon ;;
Person1 = terry,
Person2 = sharon.

?- halt.