public void addNode(Node newNode)
            {
                int comp = newNode.data.compareTo(data);
                if (comp < 0)
                {
                    if (left == null)
                    {
                        left = newNode;
                        left.parent = this;
                    }
                    else { left.addNode(newNode); }
                }
                else if (comp > 0)
                {
                    if (right == null)
                    {
                        right = newNode;
                        right.parent = this;
                    }
                    else { right.addNode(newNode); }
                }
            }