joe:
  name      : Joe
  id        : 1
  created_at: 1999-02-19 08:00
  updated_at: 1999-02-19 08:00
  # has 3 books: two old (year 1990) and one new (year 2012) book

bobby:
  name      : Bobby
  id        : 2
  created_at: 1999-02-19 08:00
  updated_at: 1999-02-19 08:00
  # has 1 old book (year 1990)

teddy:
  name      : Teddy
  id        : 3
  created_at: 1999-02-19 08:00
  updated_at: 1999-02-19 08:00
  # has no books at all