The Bookshop sells a variety of books, by a number of authors. The data kept on a particular book is listed below:
- ISBN - is a unique 13 digit commercial book identifier.
- Title - the name of the book.
- Author - the names of the persons who wrote the book.
- Genre - the type of book e.g. fiction, children, computer science text.
- Year of Publication - the year the title was printed.
- Quantity in Stock - the total number of copies of the title The Bookshop has available.
- Sale Price - the price at which the title is offered to a customer.

Write the following accessor functions in python which take a book as input and return the corresponding attribute of a book.
- get_isbn(book) – returns the isbn of the given book
- get_title(book) – returns the title of the given book
- get_authors(book) – returns the list of authors of the given book
- get_genre(book) – returns the genre of the given book
- get_year(book) – returns the year the given book was published
- get_qty(book) – returns the number of copies of the given book
- get_saleprice(book) – returns the price of the given book

Write a function co_authors which takes a book as a parameter and returns the list of co_authors if the book is written by multiple authors and returns an empty list if it is single authored. [Hint: make use of the function len to see if the book is authored by multiple persons.]

>>> co_authors(b1)
['Sussman G.', 'Sussman J.']
>>> co_authors(b2)
[ ]

Write a function check_price which takes a bookshop and an isbn and returns the corresponding sale price of the book. If the isbn does not exist print a message “Book not found”. [Use the accessor function to retrieve the isbn of the book in the bookshop]

>>> check_price(uwi_bookshop, "9780262510875")
7340.0
>>> check_price(uwi_bookshop, "978026251085")
Book not found

Write a function books_to_reorder which takes a bookshop and an integer representing reorder level. All books in the bookshop whose quantities are below this reorder are added to a list. For each book that needs to be reordered only the isbn and the titles are added to the list as tuples.

>>> books_to_reorder(uwi_bookshop,15)
[('9780262510875', 'Struc. & Interp of Comp. Prog.'), ('9780521644082', 'Haskell School of Expr.')]

Code:

def makebook(isbn,title,authors,genre,year,qtystck,saleprice):
    """constructor - creates a book"""
    return [isbn,title,authors,genre,year,qtystck,saleprice]

def bookshop():
    """constructor- creates a new bookshop"""
    return ("bookshop",[])

def add_book(book,bookshop):
    """constructor - adds a book tot eh bookshop"""
    return bookshop[1].append(book)
     
# example books
b1=["9780262510875","Struc. & Interp of Comp. Prog.",["Abelson H.","Sussman G.","Sussman J."],"CS text", 1996,12, 7340.00]
b2=["0216874068000","Algebra & No. Sys",["Hunter, J."],"Math text", 1985,30,1040.00]
b3=["9780521644082","Haskell School of Expr.",["Hudak, P."],"CS text", 2000,1,3455.00]

# code to create a uwi_bookshop
uwi_bookshop=bookshop()
add_book(b1,uwi_bookshop)
add_book(b2,uwi_bookshop)
add_book(b3,uwi_bookshop)
   
def get_isbn(book): 
    return book[0]

def get_title(book): 
     return book[1]
    
def get_authors(book): 
     return book[2]
    
def get_genre(book):
     return book[3]
    
def get_year(book): 
     return book[4]
    
def get_qty(book): 
     return book[5]
    
def get_saleprice(book): 
     return book[6]

def check_price(uwi_bookshop,book):
     for x in uwi_bookshop[1]:
         if(book == get_isbn(x)):
             return get_saleprice(x)
     print("Book not found")

def co_authors(book):
    if(len(get_authors(book)) > 1):
        mylist = get_authors(book)
        return mylist[1:]
    else:
        return []

def books_to_reorder(uwi_bookshop,num):
    lst = []
    for x in uwi_bookshop[1]:
        if(get_qty(x) < num):
            lst.append((get_isbn(x),get_title(x)))
    return lst