/**
* sets the next node linked to this node and also updates the previous node of the next to this
*/
public void setNext(Node next) {
this.next = next;
if (next != null) next.prev = this;
}
public void addChange(String graphml) {
Node first = new Node();
first.val = graphml;
first.setNext(current);
this.current = first;
}