 
       return nodes
 
-    # formats the value shown in the link labels
-    format_value: (x) -> "#{x.toFixed(2)} PJ"
-
     # callbacks
     #
     node_mouseover: ->

        transition().duration(500).
        selectAll("text.link_label").
        attr("y", (link) => @y link.right_y()).
        text((d) => @format_value d.value())

class D3.sankey.NodeList extends Backbone.Collection
  model: D3.sankey.Node

      attr("y", (d) => @y d.right_y()).
      attr("dx", -55).
      attr("dy", 2).
      style("opacity", 0)
      return links

    draw_nodes: =>
