gistfile1.txt

(defun inverser (x)
  (if (= x 1) 0 1)
  )
(defun new-state(state pos)
  (when (<= (length state) (+ pos 1)) (return-from new-state state))
  (let ((i 0)(new-list '()))
    (dolist (arrow state new-list)
      (if (or (= i pos) (= i (+ pos 1)))
            (setq new-list (append new-list (list (inverser arrow))))
        (setq new-list (append new-list (list arrow)))
        )
      (setq i (+ i 1))
      )
    )
  )
(new-state '(0 0 0 1 0 1) 3)