private static void Visitor()
{
Book earth = new Encyclopedia();
earth.name = "Big Earth!";
earth.author = "Jose S. Massey";
earth.categoryName = "Encyclopedia";
Book daily = new Magazine();
daily.name = "Daily Magazine";
daily.author = "Wayne D. Eakin";
daily.categoryName = "Magazine";
IBookExportVisitor xmlExportVisitor = new XmlExportVisitor();
IBookExportVisitor jsonExportVisitor = new JsonExportVisitor();
earth.Accept(xmlExportVisitor);
daily.Accept(jsonExportVisitor);
}