code: function (instance) {
  	if (instance.controller) {
  		var i = 0, is_changed;
  
  		for (; i < instance.change_detectors.length; ++i) {
  			if (instance.change_detectors[i].is_changed()) {
  				is_changed = true;
  			}
  		}
  
  		if (instance.controller.on_digest) {
  			instance.controller.on_digest();
  		}
  		if (is_changed && instance.controller.on_change) {
  			instance.controller.on_change();
  		}
  	}
  }
docs: /* globals /* exported ignore:end