1..50
|> Enum.map(fn(i) ->
  fn ->
    # some expensive operation
    i
  end
  |> Etude.async()
  |> Etude.retry(1) # retry once if it fails
end)
|> Etude.join(10) # concurrency of 10
|> Etude.map(&Enum.sum/1)
|> Etude.fork!()