if (number == null) return null;
	public Person findPerson(PhoneNumber number) {		Enumeration en = persons.elements();		while (en.hasMoreElements()) {			Person p = (Person) en.nextElement();			PhoneNumber[] numbers = p.getNumbers();			for (int i = 0; i < numbers.length; i++) {				if (numbers[i].getNumber().equals(number.getNumber())) {					return p;				}			}		}		return null;	}