anchor.diff:        *empty-stream*
         (lazy-cons (lazy-car str)
                    (lazy-take (lazy-cdr str) (1- n)))))
  -
  -(defun lazy-reduce2 (fn init &rest strs)
  -  (if (some #'lazy-empty? strs)
  -      init
  -      (funcall #'lazy-reduce2 fn
  -               (funcall fn init (mapcar #'lazy-car strs))
  -               (mapcar #'lazy-cdr strs))))
   
   (defun lazy-reduce (fn init str)
     (if (lazy-empty? str)
  
positive.code:   (print val)
    val)
  
  (defun integers-starting (n)
    (lazy-cons n (integers-starting (1+ n))))
  
  
negative.code: (defun force (delayed)
    (funcall delayed))
  
  (defmacro lazy-cons* (head tail)
    `(cons ,head (delay ,tail)))
  
  (defun lazy-cons (head tail)
    (cons head (delay tail)))
  
  (defun lazy-car (stream)
    (car stream))
  