code: public Object childrenAccept(MithraQLVisitor visitor, Object data) 
      {
        visitor.visit(this, data);
        if (this.children != null) {
          for (int i = 0; i < this.children.length; ++i) {
               this.children[i].jjtAccept(visitor, data);
              ((SimpleNode)this.children[i]).childrenAccept( visitor, data );
          }
        }
        return data;
      }
docs: Accept the visitor. *