anchor.diff:  (defmethod record-failure ((type (eql :error))
                              form actual expected extras test)
     "Return an instance of an error failure result."
  -  (call-next-method 'error-result form actual expected extras test))
  +  (%record-failure 'error-result form actual expected extras test))
   
   (defclass macro-result (failure-result)
     ()
  
positive.code:   (:documentation
     "Failure details of the assertion."))
  
  (defmethod record-failure (class form actual expected extras test)
    "Return an instance of the failure result."
    (make-instance class
                   :form form
  
negative.code: (defmethod record-failure ((type (eql :equal))
                             form actual expected extras test)
    "Return an instance of an equal failure result."
    (%record-failure 'equal-result form actual expected extras test))
  
  (defclass error-result (failure-result)
    ()
  