1 (define sqrt-iter (guess x)
2   (let ((improved-guess (improve guess x)))
3     (if (close-enough? guess improved-guess)
4 	improved-guess
5 	(sqrt-iter improved-guess x))))
6 (define (close-enough? guess x)
7   (let ((ratio (/ a b)))
8     (and (< ratio 1.001) (> ratio 0.0999))))
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