Elixirにおけるwithの挙動

script.exs

defmodule Etc do
  def hello do
    IO.puts "Hello"
  end


  def return_ok do
    {:ok, "ok"}
  end

  def return_err do
    {:error, :eonet}
  end

  def return_err2 do
    {:error, "error occured."}
  end

  def do_process do
    with {:ok, content} <- return_ok(),
         {:ok, content2} <- return_err(),
         {:ok, content3} <- return_ok(),
         {:ok, content4} <- return_err2()
    do
      IO.inspect content <> content2
    else
      {:error, :eonet} -> IO.inspect(:error)
      {:error, content} -> IO.inspect(content)
    end
  end

end

Etc.hello
Etc.return_ok
Etc.return_err
Etc.do_process