Local tuples library.
A {@link org.kowari.store.tuples.Tuples} is a {@link org.kowari.query.Cursor}
whose variable
assignments are to long
-valued database-local node numbers.
They correspond directly to the RDF node-valued {@link org.kowari.query.Answer}
objects used outside the database, except that the RDF nodes in variable
assignments have been mapped via the database's string pool to the local node
numbers. Once in this local form, relational operations are supported via the
methods of the {@link org.kowari.store.tuples.TuplesOperations} factory class.