1. one book on two lists
  [create B4004]
  use_count = 1
  use_count = 3 (book + 2 lists)
  local gone, use_count = 2
  newArrivals cleared, use_count = 1
  [destroy B4004]
  watcher expired: true
2. two members who point at each other (weak_ptr links)
  Ani's friend is Budi
  leaving the block...
  [destroy member Budi]
  [destroy member Ani]
end of main
