等待页面WebDriverWait

　　driver是设备，timeout是超时，poll_frequency是运行方法的时间频率

WebDriverWait(driver=driver, timeout=10, poll_frequency=0.1).until(

    EC.presence_of_element_located((By.ID, 'com.huawei.camera:id/camera_tips_layout')))
pt1 = datetime.datetime.now()