anchor.diff:  ;;
   ;; AutoLISP built-in.
   
  -;; ### list
  -;; (**list** _v_: [ll-anyp] ...): [listp]
  +;; ### (**list** _v_: [ll-anyp] ...): [listp]
   ;;
   ;; Returns a newly allocated list containing the _v_s as its elements.
   ;;
  
positive.code: 
  
  ;; # Lists
  ;; =======
  
  
  ;; ## List Predictates
  ;; -------------------
  
  ;; ### atom
  ;; (**atom** _v_: [ll-anyp]): [ll-booleanp]
  ;;
  ;; Returns `t` if _v_ is an *atom*, `nil` otherwise.
  ;;
  
negative.code: ;; AutoLISP built-in.
  
  ;; ### ll-list-length
  ;; (ll-list-length _x_: [listp]): ([ll-natnump] [null])
  ;;
  ;; Returns the length of _x_, exactly like `length`, except that if _x_
  ;; is an improper list, `nil` is returned.
  ;;
  ;; Identical to VisualLISP `vl-list-length`.
  (if (and (not *call:ignore-vlisp*)
           vl-list-length)
      (setq ll-list-length vl-list-length)
      (defun ll-list-length (x / len)
        (setq len 0)
        (while (and x
                    (listp (setq x (cdr x))))
          (setq len (1+ len)))
        (if (null x)
            len)))
  
  ;; ### (**reverse** _x_: [listp]): [listp]
  ;;
  ;; Returns a list that has the same elements as _x_, but in reverse order.
  ;;
  ;;     (reverse (list 1 2 3 4)) => (4 3 2 1)
  ;;
  ;; AutoLISP built-in.
  
  ;; ### (**append** _x_: [listp] ...): [listp]
  ;;
  ;; Returns a list that contains all of the elements of the given lists in
  ;; order.
  