anchor.diff:        (unless year (setf year 2000))
         (encode-local-time usec second minute hour day month year :timezone timezone))))
   
  +(defun parse-datestring (string)
  +  (let* ((*default-timezone* +utc-zone+)
  +         (date (parse-timestring string)))
  +    (unless (and (eq (timezone-of date) +utc-zone+)
  +                 (zerop (sec-of date))
  +                 (zerop (usec-of date)))
  +      (error "~S is not a valid date string" string))
  +    date))
  +
   (defun format-rfc3339-timestring (local-time &rest args &key omit-date-part-p omit-time-part-p
                                                omit-timezone-part-p &allow-other-keys)
     (declare (ignore omit-date-part-p omit-time-part-p omit-timezone-part-p))
  
positive.code:            #:define-timezone
             #:*default-timezone*
             #:now
             #:enable-read-macros
             #:+utc-zone+
             #:+month-names+
  
negative.code:                         :usec usec
                          :timezone (realize-timezone
                                     (or timezone *default-timezone*)))))))
  
  (defun today ()
    (minimize-time-part (now) :timezone +utc-zone+))
  
  (defun now ()
    (local-time :universal (get-universal-time)))
  