python+selenium 判断元素是否存在

@staticmethod
    def judeg_element_isexist(driver,elem_type,element):
        """
        1元素存在2元素存在多个3元素不存在
        :param driver: 浏览器
        :param elem_type:元素类型
        :param element:元素
        :return:
        """
        try:
            elements =None
            if str(elem_type).lower() =="TAG_NAME".lower():
                elements=driver.find_elements(By.TAG_NAME, element)
            elif str(elem_type).lower()=="CLASS_NAME".lower():
                elements=driver.find_elements(By.CLASS_NAME, element)
            elif str(elem_type).lower()=="ID".lower():
                elements=driver.find_elements(By.ID, element)
            elif str(elem_type).lower()=="NAME".lower():
                elements=driver.find_elements(By.NAME, element)
            if len(elements)==0:
                return 3
            elif len(elements)==1:
                return 1
            else:
                return 2
        except:
            return 3

if SeleniumTools.judeg_element_isexist(driver, "CLASS_NAME", "dian") == 3:
                    driver.back()
                    BaseFrame().debug(coder_title+"下载按钮不存在，因此跳过哦....")
                    continue