trait SlickFormatterTrait in Slick Carousel 7.3

trait SlickFormatterTrait {
  use BlazyFormatterTrait;

  /**
   * Returns the slick admin service.
   */
  public function admin() {
    if (!isset($this->admin)) {
      $this->admin = new SlickAdmin($this->manager);
    }
    return $this->admin;
  }

  /**
   * {@inheritdoc}
   */
  public function viewElements($items, $entity) {
    $entities = $this
      ->getEntitiesToView($items);

    // Early opt-out if the field is empty.
    if (empty($entities)) {
      return [];
    }

    // Collects specific settings to this formatter.
    $this->entity = $entity;
    $settings = $this
      ->buildSettings();
    $build = [
      'settings' => $settings,
    ];

    // Modifies settings before building elements.
    $this
      ->formatter()
      ->preBuildElements($build, $entities, $entity);

    // Build the elements.
    $this
      ->buildElements($build, $entities);

    // Modifies settings post building elements.
    $this
      ->formatter()
      ->postBuildElements($build, $entities, $entity);

    // If using 0, or directly passed like D8, taken over by theme_field().
    $element = $this
      ->manager()
      ->build($build);
    return $element;
  }

}