The Strategy Pattern with Lambdas
In assignment 6.5, we created an Operator enum and used method overriding to implement each operator. Now, lambdas
give us another way to express the same behavior. Create a new version of the Operator
enum that has the same behavior
but instead of using a method override, give each instance of the enum a property called operation
of type BiFunction<Integer, Integer, Integer>
that is initialized in the constructor of each enum instance. Write labmda functions to implement the four basic arithmetic operations.