Washington, president of a coporation, retires to spend the remainder of his life chopping cherry trees. The board of directors appoints Jefferson to take his place. Jefferson, however, has little experience running a corporation. He confides this information to washington, and the two enter a written agreement where Washington will serve as a part$-$time consultant to Jefferson. Washington, though wishes to ensure that he will always have time to chop his beloved cherry trees. Thus, he places the following provision in the written agreement: "I, Washington, hereby agreee to provide consulting services to Jefferson; however, i shall I only render such services if it desirable for me to do so$."$ Explain whether this agreement contains an illusory promise.