protected internal virtual Expression VisitGroupJoin(GroupJoinExpression node)
 {
     return(node.Update(
                Visit(node.Source),
                Visit(node.Joined),
                Visit(node.SourceKeySelector),
                Visit(node.JoinedKeySelector)));
 }
 protected internal virtual Expression VisitGroupJoin(GroupJoinExpression node)
 {
     return node.Update(
         Visit(node.Source),
         Visit(node.Joined),
         Visit(node.SourceKeySelector),
         Visit(node.JoinedKeySelector));
 }