anchor.diff:  (defun rassoc-not-eql-identity (item alist)
     (loop for element in alist
           when (and (not (null element))
  -		  (not (eql (cdr element) item)))
  +		  (not (eql item (cdr element))))
             return element))
           
   ;;; Special version when test-not is eq and key is given.
  
positive.code: (defun rassoc-eq-key (item alist key)
    (loop for element in alist
          when (and (not (null element))
  		  (eq (funcall key (cdr element)) item))
            return element))
    
  ;;; Special version when test is eql and key is given.
  
negative.code: (defun rassoc-test-not-key (item alist test key)
    (loop for element in alist
          when (and (not (null element))
  		  (not (funcall test item (funcall key (cdr element)))))
            return element))
    
  (defun rassoc (item alist &key key test test-not)
  