/**
  * Register a refunded amount against a purchase.
  *
  * @param \Hamjoint\Mustard\Commerce\Purchase $purchase
  * @param float $amount
  * @return void
  */
 public static function paymentRefunded(Purchase $purchase, $amount)
 {
     $purchase->refunded = time();
     $purchase->refundedAmount = $amount;
     $purchase->buyer->sendEmail('You have been refunded', 'emails.item.refunded', ['total' => $purchase->refundedAmount, 'item_name' => $purchase->item->name]);
     $purchase->save();
 }