// add a new son node as last
public void addLast(Person p)
{
if (this.isLast()) { this.getNext().addLast(p); }
else
this.setNext(new ListNode(p, p.getJob()));
}
// add a new son node as last
public void addLast(Person p)
{
if (this.isLast()) { this.getNext().addLast(p); }
else
this.setNext(new ListNode(p, p.getJob()));
}