[Cython] Possible bug (or wrong documentation) WRT "not None"

[Greg Ewing]

Samuele Kaplun wrote:
> The self parameter of a method of an extension type is guaranteed never to be 
> None. (Note: arithmetic methods might be an exception to this rule. 

The arithmetic methods don't *have* a "self" parameter
(or at least it's not always the first parameter), so
technically what the docs currently say is correct.
It's probably still worth clarifying this somehow, though.
Maybe something like

    The self parameter of a method of an extension type is guaranteed never to be
    None. (However, note that some operator methods do not always receive "self"
    as the first parameter; see <link to special_methods.html#arithmetic-methods>).

-- 
Greg