pure interface of interface Node

public interface Node
{
    public abstract void jjtOpen();
    public abstract void jjtClose();
    public abstract void jjtSetParent(Node n);
    public abstract Node jjtGetParent();
    public abstract void jjtAddChild(Node n,
                                     int i);
    public abstract Node jjtGetChild(int i);
    public abstract int jjtGetNumChildren();
}