anchor.diff:              (:values (enc 0 0 0 1 1 2013 -7) 0))
          (=>? (rfc822 "Sat, 01 Jan 2013 00:00:00+13:00")
               (:values (enc 0 0 0 1 1 2013 -13) 0))
  +       (=>? (rfc822 "Sat, 01 Mar 2008 19:42:34 -0500")
  +            (:values (enc 34 42 19 1 3 2008 5) 0))
  +       (=>? (rfc822 "Sat, 01 Mar 2008 19:42:34-0500")
  +            (:values (enc 34 42 19 1 3 2008 5) 0))
  +       (=>? (rfc822 "Sat, 01 Mar 2008 19:42:34 -05:00")
  +            (:values (enc 34 42 19 1 3 2008 5) 0))
  +       (=>? (rfc822 "Sat, 01 Mar 2008 19:42:34-05:00")
  +            (:values (enc 34 42 19 1 3 2008 5) 0))
   
          (=>? (rfc822 "Thu, 01 Jan 2004")
               (:values (enc 0 0 0 1 1 2004 0) 0))
  
positive.code:                 ;; "YYYY"
                  (4 (parse-year (parse-integer token)))
                  ;; hh:mm(:ss)?([+-]hh:?mm)? or [+-]hh:?mm
                  (t (let ((tokens (ppcre:split "-|\\+" token)))
                       (ecase (length tokens)
                         ;; "hh:mm:ss.ss", "hh:mm:ss", "hh:mm"
                         (1 (parse-time-part token))
  
negative.code:              (let ((num-days (parse-integer token)))
                 (incf universal-time (* (1- num-days) +day-secs+)))))
  
        (dolist (token (ppcre:split "(?=[+-]\\d{2}:?\\d{2})|[, -]|(?=\\d[A-Za-z]+$)"
                                    date-time-string))
          (when (string/= "" token)
            ;; Memo:
            ;; * Check whether last char is digit-char or not,
  