public bool IsPage(IGraph <IVisual, IVisualEdge> source, IVisual page) { var digidoc = new DigidocSchema(source.ThingGraph(), source.ThingOf(page)); var pageThing = source.ThingOf(page) as IStreamThing; var info = new ImageContentSpot(); return(pageThing != null && info.Supports(pageThing.StreamType)); }