如何保持下拉菜单激活并点击selenium中iframes下可用的子菜单？

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

driver = webdriver.Chrome()

driver.get('网页地址')
driver.switch_to.frame('iframe的name或id')  # 根据实际情况填写iframe的name或id属性值

dropdown_menu = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.XPATH, '下拉菜单的XPath')))
dropdown_menu.click()

sub_menu = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.XPATH, '子菜单的XPath')))
sub_menu.click()

driver.switch_to.default_content()