anchor.diff:      for key, node of @nodes
         @sys.pruneNode(key)
       @nodes = {}
  -    @edges = {}
  +    @rels = {}
   
     getSelectedNode: ->
       @selectedNode
  
positive.code:   constructor: (@sys, nodeCount) ->
      @nodes = {}
      @rels = {}
      @nodesToShow = nodeCount
      @allNodes = {}
      @allRels = {}
  
    addData: (data) ->
      @allNodes = data.nodes
  
negative.code:   setFilter: (filter) ->
      @filter = if filter then new RegExp(filter, 'i') else null
  
    setNodeCount: (n) ->
      @nodeCount = n
  
    addNodes: (nodes) ->
      return if nodes.length == 0
  