anchor.diff:                                    (integer -1000000 1000000)
                                     (integer 0 6)
                                     t
  -                                  (integer -43199 43199)
  +                                  timezone-offset
                                     simple-string))
                   decode-timestamp))
   
  
positive.code:          (ftype (function * simple-base-string) format-timestring)
           (ftype (function * fixnum) local-timezone)
           (ftype (function * (values
                               (integer -43199 43199)
                               boolean
                               string)) timestamp-subzone)
           (ftype (function (timestamp &key (:timezone timezone) (:offset (or null integer)))
  
negative.code:   (name "anonymous" :type string)
    (loaded nil :type boolean))
  
  (deftype timezone-offset ()
    '(integer -43199 50400))
  
  (define-condition invalid-timezone-file (error)
    ((path :accessor path-of :initarg :path))
    (:report (lambda (condition stream)
  