public boolean hasOverdueItems(){
		boolean overdueItemFound = false;
		for(Copy copy : itemsBorrowed){
			if(copy.isOverdue()){
				overdueItemFound = true;
			}
		}
		for(Copy copy : booksBorrowed){
			if(copy.isOverdue()){
				overdueItemFound = true;
			}
		}
		return overdueItemFound;
	}