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Suppose that you want to insist that both the Movie class and the
Sympony class have a rating method. If both use the same
rating method, then you can define it in the Attraction class,
enabling its use in all subclasses.
If the two classes use different rating methods, then your good-faith
intention to define rating in both the Movie and
Symphony subclasses may be derailed, especially if someone else is
in charge of those classes. Fortunately, Java provides a mechanism that
turns good-faith intentions into ironclad requirements.