/** Class specializing the generic merge template to intersect two sets */
public class IntersectMerge extends Merge {
  protected void aIsLess(Object a, Sequence C) { } 
  protected void bothAreEqual(Object a, Object b, Sequence C) {
    C.insertLast(a);	// add a (but not its duplicate b)
  }
  protected void bIsLess(Object b, Sequence C) { } 
}