y (yScale) {
        if (!arguments.length) {
            return this._y;
        }
        this._y = yScale;
        this.rescale();
        return this;
    }
Get or set the y scale. The y scale is typically automatically determined by the chart implementation.
@see {@link https://github.com/d3/d3-scale/blob/master/README.md d3.scale}
@param {d3.scale} [yScale]
@returns {d3.scale|CoordinateGridMixin}