public override IEnumerable <object> Invoke(object argument, Context context) { Uri link = UriEx.From((string)argument, () => ReportBadArgument(context, argument)); if (link == null) { return(null); } ReportVisitingPage(link, context); context.CurrentAddress = link; try { context.PageContent = webClient.DownloadString(link); } catch (WebException ex) { Warn(context, ex.Message); } return(null); }