Problem: Guy Buyer is buying a house from Ellen Seller over time on a land contract. During the first storm after the closing, two inches of rain poured through the roof and collected on the floor of the house. Guy has deducted the cost of fixing the roof ($2,000) from the amount that he is continuing to pay Ellen under the land contract. Ellen is now suing Guy for breach of contract because he withheld that $2,000. Please name and define the defense that Guy is most likely to use. Please explain the legal arguments that Ellen and Guy are likely to make at trial and state how you think the case would be decided.