(define seven-or-six  ; Challenge: rewrite to only have one copy of the 7
  (lambda (n)         ;  without using or.
    (if (even? n)     ; It is not fair to use something like (+ 4 3).
        7
        (if (positive? n)
            7
            6))))

(define closest-power  ; recursive version, from book
  (lambda (b n)
    (if (< n b)
        0
        (+ 1 (closest-power b (quotient n b))))))

(define helper-thing  ; iterative helper
  (lambda (b n target count)  ; note: n = b^count
    (if (< target n)
        (- count 1)
        (helper-thing b (* n b) target (+ count 1)))))

(define c-p  ; iterative replacement for closest-power
  (lambda (b target)
    (helper-thing b 1 target 0)))