public IEnumerable<Department> get_departments_in(Department department) { return catalog.get_departments_in(department); }
public IEnumerable<Product> get_products_in(Department department) { return catalog.get_products_in(department); }
public IEnumerable<Department> get_the_departments_in(Department parent_department) { return departments.get_the_departments_in(parent_department); }