/**
  * Convenience method. Returns WooCommerce base currency.
  *
  * @return string
  * @since 1.0.6
  */
 public static function base_currency()
 {
     if (empty(self::$base_currency)) {
         self::$base_currency = get_option('woocommerce_currency');
     }
     return self::$base_currency;
 }