/// <summary>
        /// Add a new set of properties to a Var
        /// </summary>
        /// <param name="v">the var</param>
        /// <param name="propertyRefs">desired properties</param>
        private void AddPropertyRefs(Var v, PropertyRefList propertyRefs)
        {
            PropertyRefList currentRefs = GetPropertyRefList(v);

            currentRefs.Append(propertyRefs);
        }
        /// <summary>
        /// Add a list of property references for this node
        /// </summary>
        /// <param name="node">the node</param>
        /// <param name="propertyRefs">list of property references</param>
        private void AddPropertyRefs(Node node, PropertyRefList propertyRefs)
        {
            PropertyRefList refs = GetPropertyRefList(node);

            refs.Append(propertyRefs);
        }