sortBubbleSize (sortBubbleSize) {
        if (!arguments.length) {
            return this._sortBubbleSize;
        }
        this._sortBubbleSize = sortBubbleSize;
        return this;
    }
Turn on or off the bubble sorting feature, or return the value of the flag. If enabled,
bubbles will be sorted by their radius, with smaller bubbles in front.
@memberof BubbleChart
@instance
@param {Boolean} [sortBubbleSize=false]
@returns {Boolean|BubbleChart}