code: function(d) {
        // create textPath element
        var path  = new SVG.TextPath
          , track = this.doc().defs().path(d)
  
        // move lines to textpath
        while (this.node.hasChildNodes())
          path.node.appendChild(this.node.firstChild)
  
        // add textPath element as child node
        this.node.appendChild(path.node)
  
        // link textPath to path and add content
        path.attr('href', '#' + track, SVG.xlink)
  
        return this
      }
docs: Create path for text to run on