Creating your own classes (cont'd)

In more conventional OOP languages, you can also start with an existing class and create a new class by extending the existing class. 

When a new class extends an existing class, an object of the new class will contain

•  All of the variables (properties in Alice) and all of the methods (class-level methods in Alice) that are defined in the existing class
• Plus all of the variables and all of the methods that are inherited into the existing class from all of its ancestors in the inheritance family tree.

In other words, all of the variables and all of the methods are inherited into an object of the new class going all the way up the family tree to the topmost class in the inheritance hierarchy.