public static function oxford(array $items, $conjunction = 'and') {
    $count = count($items);

    if ($count < 2) {
      return (string) reset($items);
    }
    elseif ($count === 2) {
      return reset($items) . ' ' . $conjunction . ' ' . end($items);
    }
    else {
      $items[] = $conjunction . ' ' . array_pop($items);
      return implode(', ', $items);
    }
  }