(deftest test-k-means()
  (check
    (let ((x (k-means 2  '((0 0)
			   (1 1)
			   (500 500)
			   (600 600)))))
      
      (and (= (aref x 0 2) (aref x 1 2))
           (= (aref x 2 2) (aref x 3 2))))))