selenium之WebDriverWait

示例代码：

from selenium.webdriver.support.wait import webdriverwait as WD

def find_element(self, by, locator):
        """
        find alone element
        :param by: eg: id, name, xpath, css.....
        :param locator: id, name, xpath for str
        :return: element object
        """
        try:
            print('[Info:Starting find the element "{}" by "{}"!]'.format(locator, by))
            element = WD(self.driver, self.outTime).until(lambda x: x.find_element(by, locator))   # 其实指driver
        except TimeoutException as t:
            print('error: found "{}" timeout!'.format(locator), t)
        else:
            return element

对于 element = WD(self.driver, self.outTime).until(lambda x: x.find_element(by, locator))如何理解？
它是说程序每隔xx秒看一眼，如果条件成立了，则执行下一步；否则继续等待，直到超过设置的最长时间，然后抛出TimeoutException异常

  def until(self, method, message=''):
        """Calls the method provided with the driver as an argument until the \
        return value is not False."""
        screen = None
        stacktrace = None

        end_time = time.time() + self._timeout
        while True:
            try:
                value = method(self._driver)
                if value:
                    return value
            except self._ignored_exceptions as exc:
                screen = getattr(exc, 'screen', None)
                stacktrace = getattr(exc, 'stacktrace', None)
            time.sleep(self._poll)
            if time.time() > end_time:
                break
        raise TimeoutException(message, screen, stacktrace)