class Book:
    def __init__(self,title, author):
        self.title = title
        self.author = author
        self.is_available = True
    def borrow(self):
        if self.is_available == False:
            print("이미 대출중입니다")
        else:
            self.is_available = False
            print(self.is_available)
            
    def return_book(self):
         self.is_available = True
         print(self.is_available)

books = Book("어린왕자","생텍쥐페리")
books.borrow()
books.borrow()
books.return_book()