/// <summary>
 /// Call the right Visit* method on the given Visitor object.
 /// </summary>
 /// <param name="visitor">Visitor to be called.</param>
 public override void VisitMe(TreeVisitor visitor)
 {
     visitor.VisitEmptyEx(this);
 }
		/// <summary>
        /// Call the right Visit* method on the given Visitor object.
        /// </summary>
        /// <param name="visitor">Visitor to be called.</param>
        public override void VisitMe(TreeVisitor visitor)
        {
            visitor.VisitEmptyEx(this);
        }