WooCommerce - Find Custom Tab Keys

<?php
  // the standard WooCommerce tab keys are "description", "reviews" and "additional_information"
  // this code will find any custom tab keys on your system
  // remove after use
  // code goes in functions.php of your child theme
  // Version 1.0
  add_filter('woocommerce_product_tabs', 'woo_tab_keys', 97);
  function woo_tab_keys($tabs) {
    foreach ($tabs as $key => $tab) {
      echo '<p>Tab key: '.$key.'</p>'.PHP_EOL;
    }
    return $tabs;
  }