Gets the term stored in an inner blackboard.
bb_get/4 retrieves a key/value tuple from an inner blackboard. OuterKey has to be a ground term! This predicate is equivalent to:
bb_get(Board, OuterKey, SubBoard), bb_get(SubBoard, InnerKey, Term)
Board blackboard OuterKey ground term InnerKey ground term Term term
bb_create(Family),
bb_put(Family, john, father, joe),
bb_put(Family, john, mother, clara),
bb_put(Family, emily, father, mike),
bb_get(Family, john, Parent, Name)
->
Parent = father
Name = joe
and
Parent = mother
Name = clara
This predicate is not part of the ISO-Prolog Standard.