renderlet (renderletFunction) {
        logger.warnOnce('chart.renderlet has been deprecated. Please use chart.on("renderlet.<renderletKey>", renderletFunction)');
        this.on(`renderlet.${utils.uniqueId()}`, renderletFunction);
        return this;
    }
A renderlet is similar to an event listener on rendering event. Multiple renderlets can be added
to an individual chart.  Each time a chart is rerendered or redrawn the renderlets are invoked
right after the chart finishes its transitions, giving you a way to modify the SVGElements.
Renderlet functions take the chart instance as the only input parameter and you can
use the dc API or use raw d3 to achieve pretty much any effect.

Use {@link BaseMixin#on on} with a 'renderlet' prefix.
Generates a random key for the renderlet, which makes it hard to remove.
@deprecated chart.renderlet has been deprecated. Please use chart.on("renderlet.<renderletKey>", renderletFunction)
@example
// do this instead of .renderlet(function(chart) { ... })
chart.on("renderlet", function(chart){
    // mix of dc API and d3 manipulation
    chart.select('g.y').style('display', 'none');
    // its a closure so you can also access other chart variable available in the closure scope
    moveChart.filter(chart.filter());
});
@param {Function} renderletFunction
@returns {BaseMixin}