/** Class for a directory storing pairs of Student objects. */
public class StudentPairDirectory {
  protected PersonPairDirectory directory;
  public StudentPairDirectory() { directory = new PersonPairDirectory (); }
  public void insert(Student s, Student t) { directory.insert(s,t); }
  public Student findOther(Student s) { return (Student) directory.findOther(s); }
  public void remove(Student s, Student t) { directory.remove(s, t); }
}