anchor.diff:                       :trans-hash (value :trans-hash)
                        :account-number (value :account-number)
                        :account-type (value :account-type)
  -                     :message-code (cdr (assoc :code message))
  -                     :message-description (cdr (assoc :description message))
  -                     :error-code (cdr (assoc :error-code err))
  -                     :error-text (cdr (assoc :error-text err))))))
  +                     :message-code (or (cdr (assoc :code message)) "")
  +                     :message-description (or (cdr (assoc :description message)))
  +                     :error-code (or (cdr (assoc :error-code err)) "")
  +                     :error-text (or (cdr (assoc :error-text err)) "")))))
   
   (defun execute (request endpoint)
     (check-type request request)
  
positive.code:    ;; LATER other fields...
     )
    (:default-initargs
     :response-code nil
      :auth-code nil
      :avs-result-code nil
      :cvv-result-code nil
      :cavv-result-code nil
      :trans-id nil
      :ref-trans-id nil
      :trans-hash nil
      :account-number nil
      :account-type nil
      :message-code nil
      :message-description nil
      :error-code nil
      :error-text nil))
  
  ;; TODO refun-transaction-response
  ;; TODO void-transaction-response
  
negative.code: 
  (defgeneric transaction-response-response-code (transaction-response))
  
  (defparameter *transaction-response-response-code-approved* "1")
  (defparameter *transaction-response-response-code-declined* "2")
  (defparameter *transaction-response-response-code-error* "3")
  (defparameter *transaction-response-response-code-held-for-review* "4")
  
  (defun transaction-response-response-code-description (transaction-response)
    (let ((response-code (transaction-response-response-code transaction-response)))
      (cond ((string= *transaction-response-response-code-approved* response-code)
             :approved)
            ((string= *transaction-response-response-code-declined* response-code)
             :declined)
            ((string= *transaction-response-response-code-error* response-code)
             :error)
            ((string= *transaction-response-response-code-held-for-review* response-code)
             :held-for-review))))
  
  (defclass auth-capture-transaction-response (transaction-response)
    ((response-code :initarg :response-code :reader transaction-response-response-code)
  