Section 64A of the Indian Sale of Goods Act is as follows : section 64 A. "In the event of any duty of customs or excise on any goods being imposed, increased, decreased or remitted after the making of any contract for the sale of such goods without stipulation as to the payment of duty where duty was not chargeable at the time of the making of the contract, or for the sale of such goods duty paid where duty was chargeable at that time, 53 (a) if such imposition or increase so takes effect that the duty or increased duty, as the case may be, or any part thereof, is paid, the seller may add so much to the contract price as will be equivalent to the amount paid in respect of such duty or increase of duty, and he shall be entitled to be paid and to sue for and recover such addition; and (b) if such decrease or remission so takes effect that the decreased duty only or no duty, as the case may be, is paid, the buyer may deduct so much from the contract price as will be equivalent to the decrease of duty or remitted duty, and he shall not be liable to pay, or be sued for or in respect of, such deduction.