如何使用正则匹配合法ip
每一段ip的情况
只有1个数字：\d\b
只有2个数字：[1-9]\d\b
只有3个数字：1\d\d\b|2[0-4]\d\b|25[0-5]\b
re.match(r"((\d\b|[1-9]\d\b|1\d\d\b|2[0-4]\d\b|25[0-5])\b\.){3}(\d\b|[1-9]\d\b|1\d\d\b|2[0-4]\d\b|25[0-5]\b)","189.9.1.89")
