code: function(datasetIndex) {
  		var ringWeightOffset = 0;
  
  		for (var i = 0; i < datasetIndex; ++i) {
  			if (this.chart.isDatasetVisible(i)) {
  				ringWeightOffset += this._getRingWeight(i);
  			}
  		}
  
  		return ringWeightOffset;
  	}
docs: Get radius length offset of the dataset in relation to the visible datasets weights. This allows determining the inner and outer radius correctly
  @private