(deftest bryan-date-math ()
  (check
    (samep "(T NIL T)" (mapcar #'leap? (list 1904 1900 1600)))
    (samep "(15 2 1998)" (multiple-value-list (date+ 17 12 1997 60)))
    (samep "(13 2 2009)" (multiple-value-list (num->date (date->num 13 2 2009))))))