Exercise 19 finished, 
 Exercise 19: (2) Create a class containing an inner class that itself contains an inner
class. Repeat this using nested classes. Note the names of the .class files produced by the
compiler.
* example in Parcel11, protected static nested class cannot be found by classes outside the out class, so it cannot be extends by them, but for other nested classes or inner class, , it can be extends
 * ExerciseNineteen.class
ExerciseNineteen$TheOne.class  
ExerciseNineteen$TheOne$TheTwo.class