anchor.diff:  
                   ((post-parameter "submit-edits")
                    (modify-data)
  +                 (flash "Your event has been updated")
  +                 (see-other url))
  +
  +                ((post-parameter "confirm-location")
  +                 (modify-data :lat lat :long long :address location)
                    (flash "Your event has been updated")
                    (see-other url))))))))))
   
  
positive.code:                       (= local-time old-local-time))
                   (try-again "You haven't entered any new details. Nothing has been changed."))
  
                  ((not (string= location old-location))
                   ; if there's a new location
                   (multiple-value-bind (latitude longitude address)
                     (geocode-address location)
  
negative.code:                   (location (or (unless (string= (post-parameter "location") "")
                                    (post-parameter "location"))
                                  old-location))
                    (lat (awhen (post-parameter "lat")
                           (unless (string= it "") (read-from-string it))))
                    (long (awhen (post-parameter "long")
                           (unless (string= it "") (read-from-string it))))
                    (new-date-p (scan +date-scanner+ (post-parameter "date")))
                    (new-time-p (scan +time-scanner+ (post-parameter "time")))
                    (date (or (when new-date-p (post-parameter "date"))
  