/// <summary>
 /// When a node is in freeze state, the node and its dependencies are
 /// deleted from AST
 /// </summary>
 /// <param name="node">The node.</param>
 internal void DeleteFrozenNodesFromAST(NodeModel node)
 {
     HashSet<NodeModel> gathered = new HashSet<NodeModel>();
     node.GetDownstreamNodes(node, gathered);
     foreach (var iNode in gathered)
     {
         syncDataManager.DeleteNodes(iNode.GUID);               
     }
 }