code: function(tag, node, controller){
      var pos = node.pos.getc(true), canvas = this.viz.canvas;
      var radius = canvas.getSize();
      var labelPos = {
        x: Math.round(pos.x + radius.width / 2),
        y: Math.round(pos.y + radius.height / 2)
      };
      tag.setAttribute('x', labelPos.x);
      tag.setAttribute('y', labelPos.y);
  
      controller.onPlaceLabel(tag, node);
    }
docs: /*
  placeLabel
  
  Overrides abstract method placeLabel in <Graph.Plot>.
  
  Parameters:
  
  tag - A DOM label element.
  node - A <Graph.Node>.
  controller - A configuration/controller object passed to the visualization.