def handle_event(:internal, event, {:check, _name, fun, acc}, %{request: request} = data) do
    case fun.(request, acc) do
      {:next, n_request} ->
        set_next_step(%{data | request: n_request}, {:event, event})

      {:dispatch, n_request} ->
        {:next_state, :dispatching, %{data | request: n_request}, [{:next_event, :internal, :dispatch}]}

      {:response, resp} ->
        {:next_state, :response, %{data | request: resp}, [{:next_event, :internal, :send_response}]}

      {:error, reason} ->
        {:next_state, :response, %{data | request: "Error, #{inspect reason}"}, [{:next_event, :internal, :send_response}]}
    end
end