code: function () {
  			var series = this,
  				points = series.points;
  			each(points, function (point) {
  				var drillId,
  					drillName;
  				if (point.node.isVisible) {
  					H.removeEvent(point, 'click');
  					if (point.graphic) {
  						point.graphic.css({ cursor: 'default' });
  					}
  
  					// Get the drill to id
  					if (series.options.interactByLeaf) {
  						drillId = series.drillToByLeaf(point);
  					} else {
  						drillId = series.drillToByGroup(point);
  					}
  
  					// If a drill id is returned, add click event and cursor. 
  					if (drillId) {
  						drillName = series.nodeMap[series.rootNode].name || series.rootNode;
  						if (point.graphic) {
  							point.graphic.css({ cursor: 'pointer' });
  						}
  						H.addEvent(point, 'click', function () {
  							point.setState(''); // Remove hover
  							series.drillToNode(drillId);
  							series.showDrillUpButton(drillName);
  						});
  					}
  				}
  			});
  		}
docs: Add drilling on the suitable points