六个名字里几个合规

示例代码里出现过这六个名字：items、total、unused、CalcTotal、calcAverage、extra_config_value。运行下面这段程序：

import re

def is_snake(name):
    return re.fullmatch(r"[a-z_][a-z0-9_]*", name) is not None

names = ['items', 'total', 'unused', 'CalcTotal',
         'calcAverage', 'extra_config_value']
ok = [n for n in names if is_snake(n)]
print(str(len(ok)) + "/" + str(len(names) - len(ok)))