showSections (showSections) {
        if (!arguments.length) {
            return this._showSections;
        }
        this._showSections = showSections;
        return this;
    }
Get or set if section header rows will be shown.
@example
chart
    .section([value], [name])
    .showSections(true|false);
@param {Boolean} [showSections=true]
@returns {Boolean|DataTable}