In other contracts, such as indemnification, an act of God may be no excuse, and in fact may be the central risk assumed by the promisor—e.g."," flood insurance or crop insurance—the only variables being the timing and extent of the damage. In many cases, failure by way of ignoring obvious risks due to "natural phenomena" will not be sufficient to excuse performance of the obligation, even if the events are relatively rare: e.g."," the year 2000 problem in computers. Under the Uniform Commercial Code, 2-615, failure to deliver goods sold may be excused by an "act of God" if the absence of such act was a "basic assumption" of the contract, and the act has made the delivery "commercially impracticable".