json.dumps() documentation is slightly incorrect.

http://docs.python.org/library/json.html#json.dumps

Reads:

  "If ensure_ascii is False, then the return value will be a unicode instance."

Should read:

  "If ensure_ascii is False, then the return value MAY BE be a unicode instance."

(Without the caps of course)

bash: python
Python 2.7.1 (r271:86832, Jun 16 2011, 16:59:05) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import json
>>> type(json.dumps({'a': 1}, ensure_ascii=False))
<type 'str'>

Tested against 2.6 and 2.7.