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));
}
