strip()疑问？

Return a copy of the string with leading and trailing characters removed. If chars is omitted or None, whitespace characters are removed. If given and not None, chars must be a string; the characters in the string will be stripped from the both ends of the string this method is called on.

好好理解最后一句

原来如此，谢谢

1 Docstring for builtins:function strip
2 ========================================
3 S.strip([chars]) -> str
4
5 Return a copy of the string S with leading and trailing
6 whitespace removed.
7 If chars is given and not None, remove characters in chars instead.