anchor.diff:    (print-unreadable-object (aint stream :type t :identity t)
       (format stream "~S" (atomic-integer-value aint))))
   
  -#-(or allegro ccl ecl sbcl)
  +#-(or allegro ccl ecl lispworks sbcl)
   (mark-not-implemented 'make-atomic-integer)
   (defun make-atomic-integer (&key (value 0))
     (check-type value %atomic-integer-value)
  
positive.code:             (:constructor %make-atomic-integer ()))
    "Wrapper for an (UNSIGNED-BYTE 64) that allows atomic
  increment, decrement and swap."
    #+(or allegro ccl ecl)
    (cell (make-array 1 :element-type t))
    #+sbcl
    (cell 0 :type %atomic-integer-value))
  
negative.code:   #+allegro `(excl:decf-atomic ,place ,delta)
    #+ccl `(ccl::atomic-incf-decf ,place (- ,delta))
    #+ecl `(- (mp:atomic-decf ,place ,delta) ,delta)
    #+lispworks `(system:atomic-decf ,place ,delta)
    #+sbcl `(- (sb-ext:atomic-decf ,place ,delta) ,delta)
    #-(or allegro ccl ecl sbcl)
    (signal-not-implemented 'atomic-decf))
  