code: function (pt) {
  		if (pt.isSum) {
  			return (pt.x === 0 ? null : "sum"); //#3245 Error when first element is Sum or Intermediate Sum
  		} else if (pt.isIntermediateSum) {
  			return (pt.x === 0 ? null : "intermediateSum"); //#3245
  		}
  		return pt.y;
  	}
docs: Return y value or string if point is sum