WC_Tax::format_tax_rate_class PHP Method

    public static function format_tax_rate_class($class)
    {
        $class = sanitize_title($class);
        $sanitized_classes = array_map('sanitize_title', self::get_tax_classes());
        if (!in_array($class, $sanitized_classes)) {
            $class = '';
        }
        return 'standard' === $class ? '' : $class;
    }

 /**
  * Whenever a WooCommerce tax rate is saved, also save the tax rate's hidden status.
  *
  * Executed whenever a WooCommerce tax rate is added, updated or deleted.
  *
  * @param int $tax_rate_id The WooCommerce Tax Rate ID.
  */
 public function save_tax_rate_hidden_status()
 {
     // nonce and cap checks are copied from WC_AJAX::tax_rates_save_changes()
     // Use return instead of exit so that WooCommerce core will handle the AJAX error messages
     if (!isset($_POST['wc_tax_nonce'], $_POST['changes'])) {
         return;
     }
     $current_class = !empty($_POST['current_class']) ? $_POST['current_class'] : '';
     // This is sanitized seven lines later.
     if (!wp_verify_nonce($_POST['wc_tax_nonce'], 'wc_tax_nonce-class:' . $current_class)) {
         return;
     }
     // Check User Caps
     if (!current_user_can('manage_woocommerce')) {
         return;
     }
     $hidden_rates = array();
     $current_class = WC_Tax::format_tax_rate_class($current_class);
     $rates = WC_Tax::get_rates_for_tax_class($current_class);
     foreach ($rates as $tax_rate_id => $rate) {
         if (isset($_POST['tax_rate_hidden'][$tax_rate_id])) {
             // @codingStandardsIgnoreEnd
             $hidden_rates[$tax_rate_id] = true;
         } else {
             if (isset($hidden_rates[$tax_rate_id])) {
                 unset($hidden_rates[$tax_rate_id]);
             }
         }
     }
     wc_hidden_taxes()->set_option('hidden_rates', $hidden_rates);
 }