minAngleForLabel (minAngleForLabel) {
        if (!arguments.length) {
            return this._minAngleForLabel;
        }
        this._minAngleForLabel = minAngleForLabel;
        return this;
    }
Get or set the minimal slice angle for label rendering. Any slice with a smaller angle will not
display a slice label.
@param {Number} [minAngleForLabel=0.5]
@returns {Number|PieChart}