anchor.diff:  ;;;;2.89
   (defun adjoin-term-dense (term term-list)
     (cond ((=zero? (coeff term)) term-list)
  -	((equ? (order term) (length term-list)) 
  +	((= (order term) (length term-list)) 
   	 (cons (coeff term) term-list))
   	(t (adjoin-term-dense term (cons 0 term-list)))))
   
  
positive.code: 	    #'(lambda (term term-list)
  		(tag (adjoin-term-sparse term term-list))))
      (my-put 'first-term '(sparse) #'first-term)
      (my-put 'rest-terms '(sparse) #'rest-terms)
      (my-put 'the-empty-termlist 'sparse #'the-empty-termlist)
      (my-put 'empty-termlist? '(sparse) #'empty-termlist?)
      (my-put 'add-terms '(sparse sparse) #'(lambda (l1 l2) (tag (add-terms l1 l2))))
      (my-put 'mul-terms '(sparse sparse) #'(lambda (l1 l2) (tag (mul-terms l1 l2))))
  
negative.code: (defun install-dense-term-list-package ()
    (labels ((tag (x) (attach-tag 'dense x))
  	   (adjoin-term-dense (term term-list)
  	     (cond ((> (order term) (length term-list))
  		    (adjoin-term-dense term (cons 0 term-list)))
  		   
  		   (t 
  		    (cons (coeff term) term-list))))
  
  
  	   (the-empty-termlist () '())
  	   	   
  	   (empty-termlist? (term-list)
  	     (null term-list))
  	   (first-term (term-list)
  	     (make-term (- (length term-list) 1) (car term-list)))
  	   (rest-terms (term-list)
  	     (cdr term-list)))
      (my-put 'adjoin-term 'dense 
  	    #'(lambda (term term-list)
  		(tag (adjoin-term-dense term term-list))))
      (my-put 'first-term '(dense) #'first-term)
      (my-put 'rest-terms '(dense) #'(lambda (termlist) (tag (rest-terms termlist))))
      (my-put 'the-empty-termlist 'dense #'(lambda () (tag (the-empty-termlist))))
      (my-put 'empty-termlist? '(dense) #'empty-termlist?)
      (my-put 'add-terms '(dense dense) #'(lambda (l1 l2) (tag (add-terms l1 l2))))
      (my-put 'mul-terms '(dense dense) #'(lambda (l1 l2) (tag (mul-terms l1 l2))))
      'done))
  (install-dense-term-list-package)
  
  
  
  (defun adjoin-term (term term-list)
    (let ((type-tags (type-tag term-list)))
  