protected function present($data, $method)
  {
    if ($data instanceof \Illuminate\Database\Eloquent\Model)
      return $data->present()->{$method}();
    elseif ($data instanceof \Illuminate\Database\Eloquent\Collection)
    {
      $arr = [];
      foreach ($data as $d)
        $arr[] = $d->present()->{$method}();
      return $arr;
    }

    return $data;
  }