Take a screenshot

def _take_screenshot(self):
        """ Take a screenshot """
        # screen size: 1280x720
        if self._fail_first_screenshot:
            self._fail_first_screenshot = False
            raise IOError("dummy fail screenshot")
        screen_path = os.path.join(__dir__, '../../tests/media/dummy_screen.png')
        screen = Image.open(screen_path)
        return screen