How to call BpmnRenderer from CustomRenderer

Hello I would like to add custom attributes to elements when rendering them using BpmnRenderer. But I am having a hard time doing so. I would like to do something like this:

MyRenderer.prototype.drawShape = function (visuals, element) {
  var bpmnRenderer = require('./../').bpmnRenderer;
  var attr = {"some" : "attribute"};
  if (is(element, 'bpmn:Task')){
      bpmnRenderer.prototype.drawShape(visuals, element, attr);
  return bpmnRenderer.prototype.drawShape(visuals, element);

The problem is that when I call this on the BpmnRenderer I get this.handlers undefined.

BpmnRenderer.prototype.drawShape = function(visuals, element) {
  var type = element.type;
  var h = this.handlers[type]; <=getting the undefined here both inside and outside if

  /* jshint -W040 */
  return h(visuals, element);

Please could you provide me with a hint or example of how to solve this issue?

Thank you

If I only red the documentation better I would save myself so much trouble. :wink: If anyone else had this problem see