string.translate( s, table[, deletechars])

Delete all characters from s that are in deletechars (if present), and then translate the characters using table, which must be a 256-character string giving the translation for each character value, indexed by its ordinal.

string.maketrans(from, to)

Return a translation table suitable for passing to translate(), that will map each character in from into the character at the same position in to; from and to must have the same length.

string.translate() 可以根据一个映射表将字符串里的字符替换成映射表对应的字符，比如映射表里面设定 a 对应 1，b 对应 2，c 对应 3，那么 'abc'.translate 对应的字符串就是 '123'.

string.maketrans() 就是用来生成 translate() 所需要的映射表，参数是两个相等的字符串，根据两个字符串对应的字符位置作成一个字符映射表。