THEM: hi there. i'd like to take all of the books.  YOU: i will keep the hat, ball and 1 book.  THEM: how about the ball and one book?  YOU: that would not work. how about the hat and one book?  THEM: i don't need a ball for anything.  YOU: ok i'll keep the hat and ball then and you can keep the books. you run a hard bargain.  THEM: great, you got a deal.