         attr("data-cid", (d) -> d.cid) # unique identifier
       # link path
       #
-      @links.append("svg:path").
+      links.append("svg:path").
         style("stroke-width", (link) -> link.value()).
         style("stroke", (link, i) -> link.color()).
         style("fill", "none").

        append("svg:svg").
        attr("height", @height).
        attr("width", @width)

      colors = d3.scale.category20()

      # links are treated as a group made of a link path and label text element
      #
      @links = @svg.selectAll('g.link').
        data(@module.links.models, (d) -> d.cid).
        enter().
        append("svg:g").

      style("opacity", 0).
      text((d) => @format_value d.value())

      return links

    draw_nodes: =>
      # Node elements are grouped inside an svg element, so we can use relative
      # coordinates
      #
      # The container just stores the x and y coordinates
      #
      nodes = @svg.selectAll("svg.node").
        data(@module.nodes.models, (d) -> d.get('id')).
        enter().
        append("svg").
