ascii() 返回对象的可打印字符串

内置函数 ascii()，Python 官方文档描述如下：

help(ascii)

Help on built-in function ascii in module builtins:

ascii(obj, /)
    Return an ASCII-only representation of an object.
    
    As repr(), return a string containing a printable representation of an
    object, but escape the non-ASCII characters in the string returned by
    repr() using \\x, \\u or \\U escapes. This generates a string similar
    to that returned by repr() in Python 2.

就像函数 repr()，返回一个对象可打印的字符串，但是非 ASCII 编码的字符，会使用 \x、\u 和 \U 来转义。

ascii(123)

'123'

ascii(None)

'None'

ascii('python')

"'python'"

ascii('嗨')

"'\\u55e8'"

repr('嗨')

"'嗨'"

'\u55e8' # 16 位十六进制数 55e8 码位的字符

'嗨'