Elixir XGen GenServer semantics discussion

fooserver.ex

defmodule FooServer do
  @behaviour :gen_server

  @server_name {:global, :foo_server}

  # Client
  def do_it do
    try do
      :gen_server.call @server_name, :foo
    catch
      :exit, reason -> {:error, reason}
    end
  end

  def do_it! do
    :gen_server.call @server_name, :foo
  end

  # Server
  def start do
    :gen_server.start_link(@server_name, __MODULE__, [], [])
  end

  def init(args) do
    {:ok, args}
  end
  def handle_call(msg, _from, state) do
    :timer.sleep(10000)
    {:reply, {:ok, :my_response}, state}
  end
  def handle_info(msg, state) do
    {:noreply, state}
  end
  def handle_cast(msg, state) do
    {:stop, {:bad_cast, msg}, state}
  end
  def terminate(_reason, _state) do
    :ok
  end
  def code_change(_old, state, _extra) do
    {:ok, state}
  end
end