(defun count-of (l x)
  (if (null l)
      0
      (+ (if (equal x (car l)) 1 0) 
	 (count-of (cdr l) x))))

(defun sum-of (l)
  (if (null l)
      0
      (+ (car l)
	 (sum-of (cdr l)))))

(defun odd-of (l &optional keep)
  (if (null l)
      keep
      (odd-of (cdr l) 
	      (if (oddp (car l))
		  (cons (car l) keep)
		  keep))))

(defun count-of-r% (l x) (count-of (flatten l) x))
(defun sum-of-r%   (l)   (sum-of   (flatten l)))
(defun odd-of-r%   (l)   (length   (odd-of (flatten l))))

(defun flatten (l)
  (let (out)
    (visit-r l #'(lambda (x) (push x out)))
    out))

(defun visit-r (thing fn)
  (if (atom thing)
      (funcall fn thing)
      (dolist (one thing)
	(visit-r one fn))))

(defun count-of-r (l x)
  (let ((out 0))
    (visit-r l #'(lambda (one) 
		   (if (equal one x) (incf out))))
    out))

(defun sum-of-r (l)
  (let ((out 0))
    (visit-r l #'(lambda (x) 
		   (incf out x)))
    out))

(defun odd-of-r (l)
  (let ((n 0))
    (visit-r l #'(lambda(x) 
		   (if (oddp x) (incf n))))
    n))