(1) A party may perform his duty through a delegate unless otherwise agreed or unless the other party has a substantial interest in having his original promisor perform or control the acts required by the contract. No delegation of performance relieves the party delegating of any duty to perform or any liability for breach.
(2) Unless otherwise agreed all rights of either seller or buyer can be assigned except where the assignment would materially change the duty of the other party, or increase materially the burden or risk imposed on him by his contract, or impair materially his chance of obtaining return performance. A right to damages for breach of the whole contract or a right arising out of the assignor's due performance of his entire obligation can be assigned despite agreementotherwise.
(4) An assignment of "the contract" or of "all my rights under the contract" or an assignment in similar general terms is an assignment of rights and unless the language or the circumstances (as in an assignment for security) indicate the contrary, it is a delegation of performance of the duties of the assignor and its acceptance by the assignee constitutes a promise by him to perform those duties. This promise is enforceable by either the assignor or the other party to the original contract.
(5) The other party may treat any assignment which delegates performance as creating reasonable grounds for insecurity and may without prejudice to his rights against the assignor demand assurances from the assignee (Section 2-609).