public override Node VisitQueryYielder(QueryYielder qy) {
bool savedFoldQuery = this.foldQuery;
this.foldQuery = true;
Block feBlock = (Block) this.Visit(qy.Source);
this.foldQuery = false;
Yielder yielder = new Yielder(this.typeSystem, this.TypeViewer);
return this.Visit(yielder.YieldTo(feBlock, qy.Body, qy.Target, qy.State));
}
