String libraries

What language has the best built-in string library? Racket's one is very poor for example, Python is much better in that regard.

http://docs.racket-lang.org/reference/strings.html
http://docs.python.org/py3k/library/stdtypes.html#string-methods

What's missing from Racket's? For most of them, you can use a regexp, for format there's, well, format.