render () {
        this._height = this._width = undefined; // force recalculate
        this._listeners.call('preRender', this, this);

        if (this._mandatoryAttributesList) {
            this._mandatoryAttributesList.forEach(e => this.checkForMandatoryAttributes(e));
        }

        const result = this._doRender();

        if (this._legend) {
            this._legend.render();
        }

        this._activateRenderlets('postRender');

        return result;
    }
Invoking this method will force the chart to re-render everything from scratch. Generally it
should only be used to render the chart for the first time on the page or if you want to make
sure everything is redrawn from scratch instead of relying on the default incremental redrawing
behaviour.
@returns {BaseMixin}