Exercise 1.43.  If f is a numerical function and n is a positive integer, then 
we can form the nth repeated application of f, which is defined to be the 
function whose value at x is f(f(...(f(x))...)). For example, if f is the 
function x ↦ x + 1, then the nth repeated application of f is the function 
x ↦ x + n. If f is the operation of squaring a number, then the nth repeated 
application of f is the function that raises its argument to the 2ⁿth power. 
Write a procedure that takes as inputs a procedure that computes f and a 
positive integer n and returns the procedure that computes the nth repeated 
application of f. Your procedure should be able to be used as follows:

((repeated square 2) 5)
625

Hint: You may find it convenient to use compose from exercise 1.42.

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(define (repeated f n)
  (if (= n 0)
      (lambda (x) x)
      (lambda (x) ((compose f (repeated f (- n 1))) x))))