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Date: Tue, 19 Aug 2014 12:34:00 -0500
From: Tim Chase <python.list@tim.thechases.com>
To: python-list@python.org
Subject: Re: 'is not' or '!='
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Xref: csiph.com comp.lang.python:76582

On 2014-08-19 20:29, Marko Rauhamaa wrote:
> The "is" relation can be defined trivially through the id()
> function:
> 
>    X is Y iff id(X) == id(Y)
> 
> What remains is the characterization of the (total) id() function.
> For example, we can stipulate that:
> 
>    X = Y
>    assert(id(X) == id(Y))

Note that a lifetime can be less than a statement:

$ python
Python 2.7.3 (default, Mar 13 2014, 11:03:55) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> id([1,2,3]) == id([4,5,6])
True


-tkc