这段源码一共切出多少个 Token

按玩具语言的规则，把下面这段源码切成 Token，输出总共有几个。

let rate = 12;
let msg = "hi there";
total = rate >= 3;

玩具语言的词法规则：关键字 let if else while；标识符以字母或下划线开头；数字是连续的数位；字符串用一对双引号括起来（不含转义）；双字符运算符 >= <= == !=；单字符运算符 + - * / = < > ; ( )；空白只做分隔。

KEYWORDS = ("let", "if", "else", "while")
TWO = ("==", "!=", ">=", "<=")
ONE = "+-*/=<>;()"
SRC = 'let rate = 12;\nlet msg = "hi there";\ntotal = rate >= 3;'

import re
pat = re.compile(r'\s+|[A-Za-z_]\w*|\d+|"[^"]*"|==|!=|>=|<=|[+\-*/=<>;()]')
n = 0
for m in pat.finditer(SRC):
    if not m.group().isspace():
        n += 1
print(n)