void start([num when])

Source 

void start([num when]) {
  if (when != null) {
    _blink.BlinkOscillatorNode.instance.start_Callback_1_(unwrap_jso(this), when);
    return;
  }
  _blink.BlinkOscillatorNode.instance.start_Callback_0_(unwrap_jso(this));
  return;
}