anchor.diff:               :with vertex fixnum := -1
                :for line :of-type (or simple-string null) := (read-line in-stream nil nil)
                :while line :do
  -             (when (and (char/= #\# (aref line 0)) (char/= #\% (aref line 0)))
  +             (when (not (comment-p line))
                  (multiple-value-bind (v adjv) (values-list (parse-line line))
                    (declare (fixnum v adjv))
                    (when (/= vertex v)
  
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:   "Parse a graph dataset file into a format that's suitable for
  consumption by Pregel+/Palgol applications and write the result out to
  a specified output file."
    (flet ((comment-p (line)
             (let ((first-char (aref line 0)))
               (or (char= #\# first-char) (char= #\% first-char))))
           (parse-line (line)
             (-<>> line
                   (split-sequence-if (lambda (c) (or (char= c #\Tab) (char= c #\space))))
                   (remove "" <> :test #'equal)
  