dr821/module/dr821m.module

<?php

/**
 * Support module for DR-821 theme.
 *
 * It implements hooks a theme cannot implement.
 */

use Drupal\Core\Block\BlockPluginInterface;

/**
 * Implements hook_block_view_alter().
 *
 * Provides this capability to the theme.
 */
function dr821m_block_view_alter(array &$build) {
  // Only activate if DR821 is the active theme.
  if (\Drupal::theme()->getActiveTheme()->getName() == 'dr821') {
    _dr821_block_view_alter($build);
  }
}