public interface Node {

  /** This method is called after the node has been made the current
    node.  It indicates that child nodes can now be added to it. */
  public void jjtOpen();

  /** This method is called after all the child nodes have been
    added. */
  public void jjtClose();

  /** This pair of methods are used to inform the node of its
    parent. */
  public void jjtSetParent(Node n);
  public Node jjtGetParent();

  /** This method tells the node to add its argument to the node's
    list of children.  */
  public void jjtAddChild(Node n, int i);

  /** This method returns a child node.  The children are numbered
     from zero, left to right. */
  public Node jjtGetChild(int i);

  /** Return the number of children the node has. */
  public int jjtGetNumChildren();

  /** perform semantic analysis, return result type */
  public Object sem () throws SemanticException;

  /** perform interpretation, return value */
  public Object run ();
}