Anne, who was unemployed, registered with the Speedy Employment Agency. A contract was then made under which Anne, in consideration of such position as the Agency would obtain for her, agreed to pay the Agency one-half of her first month's salary. The contract also contained an assignment by Anne to the Agency of one-half of her first month's salary. Two weeks later, the Agency obtained a permanent position for Anne with the Bostwick Co. at a monthly salary of $1,900. The agency also notified Bostwick of the assignment by Anne. At the end of the first month, Bostwick paid Anne her salary in full. Anne then quit and disappeared. The Agency now sues Bostwick Co. for $950 under the assignment. Who will prevail? Explain.