Suppose F is a set whose elements are functions from F to F. That's all you need to know about F. Let F be a member of F. Suppose that in F we have a function G, such that when G is applied to some input X F, it returns F applied to X applied to X, that is: G(X) = F (X(X)). Let D be G(G). Prove that D is a fixed point for F.