Which books are in good condition and have been renewed exactly twice? What percentage of books have more than 10 copies in the inventory? What is the difference in renewal counts between a borrower and the member who referred them? Given a list of (category, price) pairs for each user, where each user is allowed to borrow items from up to 3 unique categories, how can you calculate the total price of borrowed items per user? Given log entries for each book where True indicates a checkout and False indicates a return, how would you validate the logs such that: A book cannot be checked out if it's already checked out. A book cannot be returned if it's not currently checked out.