% use the directive 'external' to declare the existence of predicates % in an external package
% As a result of the declaration, the compiler will not complain % about missing predicates, and at runtime the package file will be % loaded dynamically when the external predicates are first accessed.
% For collections of predicates, use the directive 'package'
:- external(bb,[b/1,b/2]).
a(Z) :- b(X), b(X,Z).