# coding=utf8class BaseError(Exception):    def __init__(self, msg=None):        self.msg = msg    def __str__(self):        return "Error Message:{}".format(self.msg)class QueryElementError(BaseError):    def __init__(self, msg=None):        self.msg = msg or "查询元素失败"class ElementError(BaseError):    passclass ErrorKey(BaseError):    pass