(define fermat-test
  '{(composite := false)
    (while (> k 0)
           ((a := (+ 2 (rand (- n 4))))
            (n1 := n)
            (while (> n1 1)
                   ((a := (* a a))
                    (n1 := (- n1 1))))
            (if (= 1 (mod a n))
                (k := (- k 1))
                ((composite := true)
                 (k := 0)))
            (k := (- k 1))))}
  )