public async Task ChangeMenu(CoffeeService coffee, User user, string text, SlackResponse response)
{
var menu = UnpackMenu(text);
if (menu == null)
{
throw new NotWellFormedException();
}
await coffee.ChangeMenuAsync(menu);
response.Ephemeral($"{menu.Id}를 {menu.Price}원으로 수정하였습니다.");
}