anchor.diff:  
   |#
   
  +(defun is-descendant-t-n (id-1 id-2 sentence)
  +  (let ((parent (token-head (find id-1 (sentence-tokens sentence)
  +				  :key #'token-id :test #'equal))))
  +    (cond
  +      ((equal parent 0) nil)
  +      ((equal parent id-2) t)
  +      (t
  +       (is-descendant-t-n parent id-2 sentence)))))
   
   (defun range (a b)
     (assert (and (integerp a) (integerp b)))
  
positive.code:   (every (lambda (tk)
  	   (is-token-projective tk sentence))
  	 (sentence-tokens sentence)))
  
  
  (defun validate-punct (sentence)
    (let ((errors))
  
negative.code: 		(let ((ct (sentence-get-token-by-id sentence id)))
  		  (if (equal "PUNCT" (token-upostag ct))
  		      (push (list ct 'punct-causes-nonproj-of (token-id tk)) errors))))))))))
  