defp record session do
  File.mkdir_p "cache/elixircasts"
  index = session |> index
  index |> Index.record_blob("cache/elixircasts/episode.index")
  index
  |> Index.choose(fn episode -> episode[:locked] end)
  |> Index.record_lines("cache/elixircasts/closed.index")

  open = index |> Index.choose(fn episode -> !episode[:locked] end)
  open |> Index.record_lines("cache/elixircasts/open.index")
  open
  |> Enum.map(fn addr -> session |> source(addr) end)
  |> Index.record_lines("cache/elixircasts/source.index")
end