public List<ITeacher> getTeachers(Date begin, Date end){  List teachers = new ArrayList(); addTeachers(teachers, this.getWorkingEmployees(begin, end));
public List getTeachers() { List teachers = new ArrayList(); List<IEmployee> employees = this.getCurrentActiveWorkingEmployees();  addTeachers(teachers, employees);
    public List<ITeacher> getTeachers(Date begin, Date end){                List teachers = new ArrayList();             addTeachers(teachers, this.getWorkingEmployees(begin, end));                      return teachers;    }