public class Node implements Position {
    public Object element; // its element
    public Node parent;    // its parent
    public Node left;      // its left child
    public Node right;     // its right child


    public Node(Object element, Node parent, Node left, Node right) {
        this.element = element;
        this.parent = parent;
        this.left = left;
        this.right = right;
    }

    public Object element() {
        return element;
    }
}