try:
        element = None
        if by == "id":
            element = self.driver.find_element_by_id(value)
        elif by == "name":
            element = self.driver.find_element_by_name(value)
        elif by == "css":
            element = self.driver.find_element_by_css(value)
        elif by == "class":
            element = self.driver.find_element_by_class(value)
        elif by == "xpath":
            element = self.driver.find_element_by_xpath(value)
    except:
        print("定位by和value有问题")
    return element
    
    #运行代码
request_driver = SeleniumDriver()
request_driver.get_url("https://www.imooc.com/user/newlogin")
request_driver.get_element("name","email")