anchor.diff:  
   (defmethod get-and-check-alphanum ((self iban) string &optional length)
     (when (and length (/= length (length string)))
  -    (signal 'iban-error
  -            :format-control "For IBAN ~S:~%   Bad length,  expected ~D, got ~D: ~S" 
  -            :format-arguments (list self length (length string) string)))
  +    (error 'iban-error
  +           :format-control "For IBAN ~S:~%   Bad length,  expected ~D, got ~D: ~S" 
  +           :format-arguments (list self length (length string) string)))
     (map 'string (lambda (ch) 
                    (let ((index (position ch +alphabet-from+)))
                      (unless index 
  -                     (signal 'iban-error
  -                             :format-control "For IBAN ~S:~%    Bad character '~C' in ~S, ~
  +                     (error 'iban-error
  +                            :format-control "For IBAN ~S:~%    Bad character '~C' in ~S, ~
                                 should be alphanumeric."
  -                             :format-arguments (list self ch string)))
  +                            :format-arguments (list self ch string)))
                      (aref +alphabet-from+ (if (< index 36) index (- index 26)))))
          string))
   
   
  -(defparameter +country-codes+
  -  (mapcar
  -   (function third)
  -   (com.informatimago.common-lisp.cesarum.iso3166:get-countries :only-existing t))
  +(defun country-codes ()
  +  "Returns a list of 2-letter country codes."
  +  (mapcar (function first)
  +          (get-countries :only-existing t)))
  +
  +(defparameter *country-codes* (country-codes)
     "List of 2-letter country codes.")
   
   
  
positive.code: ;;;;AUTHORS
  ;;;;    <PJB> Pascal J. Bourguignon <pjb@informatimago.com>
  ;;;;MODIFICATIONS
  ;;;;    2012-11-29 <PJB> Added a PRINT-OBJECT method, corrected SIGNAL calls,
  ;;;;                     added examples to the package comment.
  ;;;;    2004-10-10 <PJB> Created.
  ;;;;BUGS
  
negative.code: "
    (= 1 (mod
          (loop
            :for ch :across (concatenate 'string (subseq iban 4) (subseq iban 0 4))
            :with n = 0
            :do (setf n (+ (* (if (alpha-char-p ch) 100 10) n)
                           (parse-integer (string ch) :radix 36 :junk-allowed nil)))
            :finally (return n)) 97)))
  
  
  (defun compute-iban-key (country account)
  