conventions/requirements for 'is' vs '==', 'not vs '!=', etc

[Gabriel Genellina]

En Mon, 19 May 2008 17:58:48 -0300, bruno.desthuilliers at gmail.com  
<bruno.desthuilliers at gmail.com> escribió:

> On 19 mai, 22:29, Luis Zarrabeitia <ky... at uh.cu> wrote:
> (snip)
>> The main
>> concept here: identity [usually] implies equality,
>
> I really enjoyed the "usually" disclaimer !-)

In some *rare* cases, identity does not imply equality:

py> inf = 1e300*1e300
py> nan = inf-inf
py> nan
-1.#IND
py> nan is nan
True
py> nan == nan
False

-- 
Gabriel Genellina