What is the point of an identity function if it's just the same as the original function?
Identity function serves as the "base" of all other functions. For example, if you are dealing with a function of functions, then the base case of this function may return an identity function.

Consider a simple function-generating function `g(n) = f^n; f^n(x) = x * n`. It is clear that `g(1) = f^1` is an identity function, since `f^1(x) = x * 1 = x` for all x. Here, identity function serves as the base function when we analyze `g` at different values of `n`.