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)
      };
  
      var style = tag.style;
      style.left = labelPos.x + 'px';
      style.top = labelPos.y + 'px';
      style.display = '';
  
      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.