csv using "and"

HumanList.php

class HumanList {

  use \Drupal\Core\StringTranslation\StringTranslationTrait;

  public function __invoke(array $items): string {
    $last = array_pop($items);

    return $this->t(':items and :item', [
      ':items' => implode(', ', $items),
      ':item' => $last,
    ]);
  }
}