anchor.diff:  (defun mysql-time-interval-to-seconds (interval)
     (assert (typep interval 'mysql-time-interval))
     (with-prefixed-accessors (negativep days hours minutes seconds microseconds)
  -      (mysql-time-interval- interval)
  -    (* (if negativep -1 1)
  -       (+ seconds
  -          (* +seconds-per-minute+
  -             (+ minutes
  -                (* +minutes-per-hour+
  -                   (+ hours
  -                      (* +hours-per-day+ days)))))))))
  -
  -(defun seconds-to-mysql-time-interval (value)
  +    (mysql-time-interval- interval)
  +    (values (* (if negativep -1 1)
  +               (+ seconds
  +                  (* +seconds-per-minute+
  +                     (+ minutes
  +                        (* +minutes-per-hour+
  +                           (+ hours
  +                              (* +hours-per-day+ days)))))))
  +            microseconds)))
  +
  +(defun seconds-to-mysql-time-interval (value &optional (microseconds 0))
     (assert (typep value 'integer))
     (let ((negativep (minusp value))
           (value (abs value)))
  
positive.code:                          :days days
                           :hours hours
                           :minutes minutes
                           :seconds seconds))))))
  
  (defun parse-time-interval-string (str)
    (let ((negativep (starts-with str "-")))
  
negative.code:                    :day day
                     :hour hour
                     :minute minute
                     :second second
                     :microsecond microseconds)))
  
  (defun parse-date-time-string (str)
    (let ((year 0) (month 0) (day 0)
  