public virtual TResult VisitNode(GraphMemberInfoNodeViewModel graphMemberInfo, TInput input) => DefaultVisit(graphMemberInfo, input);
 public virtual TResult VisitNode(GraphMemberInfoNodeViewModel graphMemberInfo) => DefaultVisit(graphMemberInfo);
 public virtual IEnumerable <TreeNodeViewModel> VisitNodeAndBuildChildren(GraphMemberInfoNodeViewModel graphMemberInfo, bool expandChildren,
                                                                          CancellationToken cancellation) =>
 Enumerable.Empty <TreeNodeViewModel>();