John is a motorcycle repairman who owns a small repair shop out of his home. Driving by his neighbor's yard, John sees a large metal shed for sale. John calls the neighbor and offers to buy to use as an expansion of his repair shop. John wants to dismantle the shed in the neighbor's yard and move it to his own yard. Neighbor accepts John's offer and makes an offer in return, if John will help the neighbor dismantle the shed, neighbor will help John reassemble the shed in John's yard. They agree to have the moving process done in two weeks. John helps the neighbor dismantle the shed and move it to his own yard, turning down a couple of repair jobs in order to get the move done. Once the shed pieces are moved to John's yard, neighbor then refuses to help John reassemble it, making John have to do it himself. Can John recover anything from the neighbor, and through what theory?