     GenServer.cast(server, {:puts, str |> String.upcase |> String.replace(~r/[^A-Z ]+/, "")})
   end
 
+  ##
   ## server callbacks
+  ##
 
   @delay_during        500
   @delay_after         500

defmodule UpsideDownLeds.BlinkingLights do
  use GenServer

  ## client API

  @doc """
  Starts the server.

  end

  defp blink(pid, delay_during \\ @delay_during, delay_after \\ @delay_after) do
    ElixirALE.GPIO.write(pid, 0)
    :timer.sleep(delay_during)
    ElixirALE.GPIO.write(pid, 1)
    :timer.sleep(delay_after)
  end
end
