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
