How to decode strings in Emacs Lisp?

I'm writing an Emacs extension and want to fetch some data from the Internet. Using url-retrieve-synchronously and some simple text processing I can get a string like

"\273\313\2开发者_高级运维71\311\267\335 abcd"

The first several characters are encoded in GBK, I'd like to know how to decode them? Many thanks.

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See decode-coding-string.