The Book Class The instance data of the Book class is the book's title and author, stored as strings in variables named title and author. The class should include the following methods: __init__ - The initializer should accept the book's title and author as parameters and store them in the instance variables. __str__ - The string function should return a description of the book in the form 'title by author', such as 'Dune by Frank Herbert'. The Library Class The instance data of the Library class is a list of Book objects called collection (Web-CAT will be doing some testing based on that name). The class should include the following methods: __init__ - The initializer should accept no parameters and simply set up an initially empty collection of books.