n2 Although § 554.2615 expressly mentions sellers only, we have said it equally applies to buyers. Nora Springs Coop. Co. v. Brandau, 247 N.W.2d 744, 748 (Iowa 1976). [Editorial note:  Consider the second paragraph of Official Comment 9 to UCC 2-615.  Do the examples used in that paragraph suggest the doctrine of frustration of purpose rather than the doctrine of impracticability?]