equalRingSizes () {
        return this.relativeRingSizes(
            ringCount => {
                const result = [];
                for (let i = 0; i < ringCount; i++) {
                    result.push(1 / ringCount);
                }
                return result;
            }
        );
    }
Constructs a RingSizes parameter for {@link SunburstChart#ringSizes ringSizes()}
that will make the chart rings equally wide.

@example
  var chart = new dc.SunburstChart(...);
  chart.ringSizes(chart.equalRingSizes())
@returns {RingSizes}