撸代码时判断识别是否成功我用的上面示例的msg，但实际返回参数并没有。识别成功返回{"log_id": 2520519803438148916, "words_result_num": 10, "words_result": {"证号": {"words": "440882199407247218"}, "有效期限": {"words": "20131112"}, "准驾车型": {"words": "C1"}, "住址": {"words": "广东省霞州市乌石镇吴宅村55号"}, "至": {"words": "20191101"}, "姓名": {"words": "吴伟文"}, "国籍": {"words": "中国"}, "出生日期": {"words": "19940724"}, "性别": {"words": "男"}, "初次领证日期": {"words": "20131101"}}}， 识别失败返回  {"log_id": 7354976359365269, "words_result_num": 10, "words_result": {"证号": {"words": ""}, "有效期限": {"words": "年"}, "准驾车型": {"words": "C1"}, "有效起始日期": {"words": ""}, "住址": {"words": ""}, "姓名": {"words": ""}, "国籍": {"words": ""}, "出生日期": {"words": ""}, "性别": {"words": "男"}, "初次领证日期": {"words": ""}}} ，那么得怎么判断识别成功或否？