A party may terminate the contract where the failure of the other party to perform an obligation under the contract amounts to a fundamental nonperformance. The right of a party to terminate the contract is exercised by notice to the other party. If performance has been offered late or otherwise does not conform to the contract the aggrieved party will lose its right to terminate the contract unless it gives notice to the other party within a reasonable time after it has or ought to have become aware of the offer or of the non-conforming performance. On termination of a contract to be performed at one time either party may claim restitution of whatever it has supplied under the contract, provided that such party concurrently makes restitution of whatever it has received under the contract. If restitution in kind is not possible or appropriate, an allowance has to be made in money whenever reasonable.