anchor.diff:    (:export #:run-iterations
   	   #:remove-dangling-nodes
   	   #:remove-serial-nodes
  +	   #:remove-parallel-edges
   	   #:randomized-bfs))
   
   (in-package :ttnr)
  
positive.code: 	     ((candidates (remove-if
  			   #'(lambda (x) (member x exclusions :test #'bmg:node-equal))
  			   (collect-nodes-by-degree graph 2))))
  	   (unless candidates (return-from remove-serial-nodes removed))
  	   (incf removed)
  	   (remove-serial-node graph (first candidates))))))
  
  
  (defun randomized-bfs (start-node goal-node
  
negative.code: 
  (defun remove-dangling-nodes (graph preservables)
    (let* ((visited (make-hash-table :test #'eq))
  	 (queue (collect-nodes-by-degree graph 1))
  	 (removed 0))
      (loop while queue do
  	 (let
  	     ((current-node (pop queue)))
  