Given the following code snippet, what will be the output?

Given the following code snippet, what will be the output?

String mainWindow = driver.getWindowHandle();
Set allWindows = driver.getWindowHandles();
for(String window : allWindows) {
  if(!window.equals(mainWindow)) {
    driver.switchTo().window(window);
    System.out.println(driver.getTitle());
  }
}