string.
ascii_lowercase
='abcdefghijklmnopqrstuvwxyz'
string.
ascii_uppercase
='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
string.
ascii_letters
='abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
string.
digits
='0123456789'
string.
hexdigits
='0123456789abcdefABCDEF'
string.
octdigits
='01234567'
string.
punctuation
标点符号 !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
string.whitespace
空白符 space,tab,换行等
string.
printable
可打印字符,以上所有集合