the domain model the book class is simple value type class (that is it is data oriented with no behaviour of its own)class bookdef __init__(selfisbntitleauthorprice)self isbn isbn self title title self author author self price price def __str__(self)return self title by self author str(self pricethe bookshop class holds list of books and provides set of methods to access booksupdate books and delete booksclass bookshopdef __init__(selfbooks)self books books def get(selfisbn)if int(isbnlen(self books)abort( return list(filter(lambda bb isbn =isbnself books))[ def add_book(selfbook)self books append(bookdef delete_book(selfisbn)self books list(filter(lambda bb isbn !isbnself books)in the above codethe books attribute holds the list of books currently available the get(method returns book given specified isbn the add_book(method adds book object to the list of books the delete_book(method removes book based on its isbn the bookshop global variable holds the bookshop object initialised with default set of books