def booking(self): """Заказ издания.""" if self.count > 0: self.count -= 1 self.demand += 1 self.sold += 1 self.book.income += self.retail_markup BookStore.log(f'bought book {str(self)} for {self.retail_markup}') return self.retail_markup else: self.demand += 1 BookStore.bid_book(self) BookStore.log(f"can't buy book {str(self)} ") return 0