class book:
    def __init__(self, id, title, author, isAvailable):
        self.id = id
        self.title = title
        self.author = author
        self.isAvailable = isAvailable       
                
    def rent():
        self.isAvailable = False
        
    def release():
        self.isAvailable = True 
        
class user:
    def __init__(self, id, name, surename, hasBooks):
        self.id = id
        self.name = name
        self.surename = surename
        self.hasBooks = hasBooks  

# Some Testing
book_test = book(1, "Harry Potter - Stein der Weisen", "Joanne K. Rowling", False)
print(book_test.title)

user_testHasBooks = []
user_test = user(1, "Maik", "Riecken", user_testHasBooks)
print(user_test.surename)