library library library | Python Fiddle

#!/usr/local/bin/python3
import shelve

class Library:
    def __init__(self, fn):
        self.fn = fn
        self.shelf = shelve.open(fn)

def add(self, book):
        self.shelf[book.isbn] = book

def get_by_isbn(self, isbn):
       return self.shelf[isbn]

def get_by_title(self, title):
        for book in self.shelf.values():
            if book.title == title:
                return book
        return None

def get_by_author(self, author):
        for book in self.shelf.values():
            for a in book.authors:
                if a == author:
                    return book
        return None

def close(self):
        self.shelf.close()

class Book:
    def __init__(self, isbn, title, authors):
        self.isbn, self.title, self.authors = isbn, title, authors

def __eq__(self, other):
        if type(other) is type(self):
            return self.__dict__ == other.__dict__
        return False

def __ne__(self, other):
        return not self.__eq__(other)

class Author:
    def __init__(self, first_name, middle_name, last_name):
        self.first_name, self.middle_name, self.last_name = first_name, middle_name, last_name

def __eq__(self, other):
        if type(other) is type(self):
            return self.__dict__ == other.__dict__
        return False

def __ne__(self, other):
        return not self.__eq__(other)

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