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(define (words x)
        (cond ((= x 1) (display "pre one "))
                ((= x 2) (display "post one "))
                ((= x 3) (display "pre two "))
                ((= x 4) (display "post two "))
                ((= x 5) (display "pre three "))
                ((= x 6) (display "post three "))
                ((= x 7) (display "pre four "))
                ((= x 8) (display "post four "))))
 ...

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(define (fib x)
        (define (fib-iter a b cur)
                (cond ((= cur 0) b)
                        ((fib-iter (+ a b) a (- cur 1)))))
        (fib-iter 1 0 x))
(display (fib 3))
(display (fib 4))
(display (fib 5))
(display (fib 6))

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(define (fib x)
        (define (fib-iter a b cur)
                (cond ((= cur 0) b)
                        ((fib-iter (+ a b) a (- cur 1)))))
        (fib-iter 1 0 x))
(display (fib 3))

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(define (words x)
        (cond ((= x 1) (display "pre one"))
                ((= x 2) (display "post one"))
                ((= x 3) (display "pre two"))
                ((= x 4) (display "post two"))))
                
(define (story y)
        (cond ((<= y 4) (words y) (story (+ y 2)) (words (+ y 1)))))
        

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(define (words x)
        (cond ((= x 1) (display "pre one"))
                ((= x 2) (display "post one"))
                ((= x 3) (display "pre two"))
                ((= x 4) (display "post two"))))
                
(define (story y)
        (cond ((<= y 2) (words y) (story (+ y 2)) (words (+ y 1)))))
        

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(define (words x)
        (cond ((= x 1) (display "pre one"))
                ((= x 2) (display "post one"))
                ((= x 3) (display "pre two"))
                ((= x 4) (display "post two"))))
                
(define (story y)
        (cond ((<= y 2) (words y) (story (+ y 2)) (words (+ y 1)))))

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(define (words x)
        (cond ((= x 1) (princ "pre one"))
                ((= x 2) (princ "post one"))
                ((= x 3) (princ "pre two"))
                ((= x 4) (princ "post two"))))
                
(define (story y)
        (cond ((<= y 2) (words y) (story (+ y 2)) (words (+ y 1)))))

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(define (words x)
        (cond ((= x 1) (print "pre one"))
                ((= x 2) (print "post one"))
                ((= x 3) (print "pre two"))
                ((= x 4) (print "post two"))))
                
(define (story y)
        (cond ((<= y 2) (words y) (story (+ y 2)) (words (+ y 1)))))

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(define (words x)
        (cond ((= x 1) "pre one")
                ((= x 2) "post one")
                ((= x 3) "pre two")
                ((= x 4) "post two")))
                
(define (story y)
        (cond ((<= y 2) (words y) (story (+ y 2)) (words (+ y 1)))))

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; string rotation
 
(define (string-find pat str . s)
  (let* ((plen (string-length pat))
         (slen (string-length str))
         (skip (make-vector plen 0)))
    (let loop ((i 1) (j 0))
      (cond ((= i plen))
            ((char=? (string-ref pat i) (string-ref pat j))
 ...

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; string rotation
 
(define (string-find pat str . s)
  (let* ((plen (string-length pat))
         (slen (string-length str))
         (skip (make-vector plen 0)))
    (let loop ((i 1) (j 0))
      (cond ((= i plen))
            ((char=? (string-ref pat i) (string-ref pat j))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define foldl
  (lambda (lst op base)
    (if (null? lst) base
      (foldl (cdr lst) op (op base (car lst))))))
 
(define foldr
  (lambda (lst op base)
    (if (null? lst) base
      (op (car lst) (foldr (cdr lst) op base)))))
 ...

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(define (climb start step test)
  (if (test start)
      start
      (climb (step start) step test)))
 
(define (binary-search start end test)
  (let* ((mid (round (+ start
                        (/ (- end 
                              start) 
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...

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(define square
(lambda (x)
(* x x)))
 
(define exp
(lambda (a b)
(cond ((= 0 b) 1)
((even? b) (square (exp a (/ b 2))))
(else (* a (exp a (- b 1)))))))
 ...