code: public boolean hasHandlers(int eventBits, String eventName, Function handler) {
      for (int i = 0, j = elementEvents.length(); i < j; i++) {
        BindFunction function = elementEvents.get(i);
        if ((function.hasEventType(eventBits) || function.isTypeOf(eventName))
           && (handler == null || function.isEquals(handler))) {
          return true;
        }
      }
      return false;
    }
docs: Return true if the element is listening for the
  given eventBit or eventName and the handler matches.