def refund amount_in_cents = nil
      return false unless link? :refund
      refund = self.class.from_response(
        follow_link :refund, :params => { :amount_in_cents => amount_in_cents }
      )
      refund.uuid == uuid ? copy_from(refund) && self : refund
    end
def refund amount_in_cents = nil
      return false unless link? :refund
      refund = self.class.from_response(
        follow_link :refund, :params => { :amount_in_cents => amount_in_cents }
      )
      refund.uuid == uuid ? copy_from(refund) && self : refund
    end
Refunds the transaction.

 @return [Transaction, false] The updated original transaction if voided,
   a new refund transaction, false if the transaction isn't voidable or
   refundable.
 @raise [Error] If the refund fails.
 @param amount_in_cents [Integer, nil] The amount (in cents) to refund
   (refunds fully if nil).