public HtmlCourtsInfoFetcher(IDataParserHandler parser)
        {
            Requires.NotNull(parser, "parser");
            Parser = parser;

            Parser.ViabilityObserver = ViabilityObserver;

            CacelOperation = () => Parser.Cancel();
        }
        public override void Cancel()
        {
            IsCancellationRequested = true;
            if (Successor != null)
            {
                Successor.Cancel();
            }

            if (Failer != null)
            {
                Failer.Cancel();
            }
        }