anchor.diff:                            (if (> part-count 3) (days-in-month month year) day)
                             month
                             year
  -                          :offset offset
                             :timezone timezone
                             :into into)))))
   
  
positive.code:             timestamp-parts)
      (multiple-value-bind (nsec sec min hour day month year day-of-week daylight-saving-time-p offset)
          (decode-timestamp timestamp :timezone timezone)
        (declare (ignore nsec day-of-week daylight-saving-time-p))
        (let ((month (if (> part-count 4) 12 month)))
          (encode-timestamp 999999999
                            (if (> part-count 0) 59 sec)
  
negative.code:             timestamp-parts)
      (multiple-value-bind (nsec sec min hour day month year day-of-week daylight-saving-time-p offset)
          (decode-timestamp timestamp :timezone timezone)
        (declare (ignore nsec day-of-week daylight-saving-time-p offset))
        (encode-timestamp 0
                          (if (> part-count 0) 0 sec)
                          (if (> part-count 1) 0 min)
  