private static RetailCustomer ReadRetail(XmlReader xmlIn)
 {
     RetailCustomer customer = new RetailCustomer();
     customer.FirstName = xmlIn.ReadElementContentAsString();
     customer.LastName = xmlIn.ReadElementContentAsString();
     customer.Email = xmlIn.ReadElementContentAsString();
     customer.HomePhone = xmlIn.ReadElementContentAsString();
     return customer;
 }
 private static void WriteRetail(RetailCustomer customer, XmlWriter xmlOut)
 {
     xmlOut.WriteStartElement("Customer");
     xmlOut.WriteElementString("Type", "Retail");
     xmlOut.WriteElementString("FirstName", customer.FirstName);
     xmlOut.WriteElementString("LastName", customer.LastName);
     xmlOut.WriteElementString("Email", customer.Email);
     xmlOut.WriteElementString("HomePhone", customer.HomePhone);
     xmlOut.WriteEndElement();
 }