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This should not be surprising in that the cond statement was part of the invariant function template for all lists.    This tells us that differentiation between base and inductive cases is fundamental to the nature of lists.    Scheme is unable to express this fact in its structural representations of data, i.e. structs, so we were forced to represent it in terms of an invariant function template.    Java, however, has the ability to express this relationship in terms of its inheritance hierarchy and thus we use delegation to leverage this "polymorphic" behavior of the IntList sub-classes to let them differentiate themselves.

NO COND!!

 Exercises:

1. Add method to your lists classes that will calculate the product of all the elements.
2. Add a method to return a copy of your list.
3. Add a method to return all the positve values in the list. 
4. Add methods to return the largest/smallest element of the list.  
   • Integer.MAX_VALUE and Integer.MIN_VALUE are static fields of the Integer class that will give you the largest and smallest possible integer values in Java.
   • For simplicity's sake, just return the appropriate value above in the situation where no min or max value exists in the list.   We will learn how to throw exceptions later.

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