Give an example of an assignment of rights and explain the relationship of the parties

An assignment of rights is the voluntary transfer to a third party of the rights arising from a contract. Ann promises to sell Bart an automobile for which Bart promises to pay $10,000 in monthly installments over the next three years. Ann's right under the contract is to receive payment from Bart, whereas Ann's duty is to deliver the automobile. Bart's right is to receive the automobile; his duty is to pay for it. If Ann were to transfer her right under the contract (the installment payments due from Bart) to Clark for $8,500 in cash, this would constitute a valid assignment of rights. In this case, Ann would be the assignor, Clark would be the assignee, and Bart would be the obligor. After the assignment, Bart would be obligated to make payments to Clark instead of Ann.