locale_translatable_language_list example

  public function getFormId() {
    return 'locale_translation_status_form';
  }

  /** * Form builder for displaying the current translation status. * * @ingroup forms */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $languages = locale_translatable_language_list();
    $status = locale_translation_get_status();
    $options = [];
    $languages_update = [];
    $languages_not_found = [];
    $projects_update = [];
    // Prepare information about projects which have available translation     // updates.     if ($languages && $status) {
      $updates = $this->prepareUpdateData($status);

      // Build data options for the select table.