Create a base class titled ReadingMaterial. Include subclasses of Online, Book, and Magazine. Design your classes so that common characteristics are placed in the ReadingMaterial class. Provide the unique characteristics of the subclasses in the derived classes. Define an interface called IPrintable that has a method that returns as a string how it is available in hard copy form (i.e., printable PDF, from a publisher or from a bookstore). Include a presentation class to test your design.