anchor.diff:  	   (remove-serial-node graph (first candidates))))))
   
   
  +(defun combine-parallel-edge-weights (weights)
  +  (- 1 (apply #'* (mapcar #'(lambda (weight) (- 1 weight)) weights))))
  +
  +
   (defun remove-parallel-edges-helper (graph)
     (let*
         ((removed 0)
  
positive.code: 
  (defun remove-parallel-edges (graph)
    (let
        ((removed 0))
      (loop do
  	 (let
  	     ((removed-this-round (remove-parallel-edges-helper graph)))
  	   (incf removed removed-this-round)
  
  	   (when (= 0 removed-this-round)
  	     (progn
  	       (format *error-output* "Removed ~A parallel edges~%" removed)
  	       (return-from remove-parallel-edges removed)))))))
  
  
  (defun randomized-bfs (start-node goal-node
  
negative.code: 		 (bmg:remove-node graph current-node)
  		 (incf removed)))))
      (format *error-output* "Removed ~A dangling nodes~%" removed)))
   
  
  (defun collect-neighbors (nodes)
    "Collects all the neighboring nodes of given list of nodes."
  