uswds-8.x-2.1-rc1/preprocess/block/block__system_menu_block__primary_menu.preprocess.inc

<?php

/**
 * @file
 * Preprocess function for this hook.
 */

/**
 * Implements hook_preprocess_block__DELTA__REGION().
 *
 * This made possible by our custom theme suggestion.
 *
 * @see uswds_theme_suggestions_block_alter()
 */
function uswds_preprocess_block__system_menu_block__primary_menu(&$variables) {
  _uswds_mark_menu_items($variables, 'primary_menu');
}