Finished 'initialize' methods for all three classes
added 'add_book' method to Library
added getter methods for book title and status, added list_books method
checkout procedure mostly good, keeps track of borrowers number of books, makes sure a book is available for checkout.
Fixed checkout process to display an error if the book is unable to be checked out
working through the end of main.rb, not fully commented
has all beginning functionality, has basic check-in method(untested), needs lots of commenting
fully functional, needs additional comments
finished library.rb with basic requirements
completed lesson extension 6, plus @year_published and @edition attributes
finished extension 7 with ability to add ratings to books