protected WebElement findElement(final String by, final String using) {
    final OperaWebElement el = this;

    return parent.implicitlyWaitFor(
        new Callable<WebElement>() {
          public WebElement call() {
            return parent.findElement(by, using, el);
          }
        });
  }
  private void assertElementDisplayed(String message) {
    Boolean displayed =
        parent.implicitlyWaitFor(
            new Callable<Boolean>() {
              public Boolean call() {
                return isDisplayed();
              }
            });

    if (displayed == null || !displayed) {
      throw new ElementNotVisibleException(message);
    }
  }