Lab 18. Subtype Inherits Openness of Base Type

Open appliances.xsd and examine it. It defines a 
base type, appliance.

Open juicers.xsd and examine it. It defines a type,
juiceAppliance, that extends appliance.

You are to give the base type open content. In
juicers.xml notice that you can add extension 
elements anywhere within the <juicer> element,
i.e. juiceAppliance has inherited the openness
of appliance!
