According to <http://zlib.net/manual.html#Advanced>, the deflateInit2(windowBits) parameter can be:

* +8 to +15 to include a “zlib” header and trailer
* −8 to −15 to write a raw Deflate stream with no header nor trailer
* 16 + (8 to 15) to include a basic “gzip” header and trailer

The inflateInit2(windowBits) parameter can also be set to the above values to specify what header and trailer to expect, and it can also be set to 0 to read the window size from the “zlib” header itself.

Assuming that the Python module passes “wbits” straight through to the actual “zlib” module, I think these points could be clarified in the Python documentation.