anchor.diff:               (write-vertex vertex adjvs)
                (add/set-written-vertex vertex chvs))
             ;; Next, we write the remaining unwritten leaf vertices in
  -          ;; the chvs set to the output file
  +          ;; the chvs hash table to the output file
             (when (< 0 (hash-table-count chvs))
               (maphash (lambda (v s)
                          (when (eql s :unwritten)
  
positive.code:          (add/set-written-vertex (vid ht)
             (when (not (eql (gethash vid ht) :written))
               (setf (gethash vid ht) :written))))
      (declare (inline parse-line
                       write-vertex
                       add-unwritten-vertex
                       add/set-written-vertex))
  
negative.code:              :with vertex fixnum := -1
               :for line :of-type (or simple-string null) := (read-line in-stream nil nil)
               :while line :do
               (when (not (comment-p line))
                 (multiple-value-bind (v adjv) (values-list (parse-line line))
                   (declare (fixnum v adjv))
                   (when (/= vertex v)
  