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From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: checking if two things do not equal None
Date: Sat, 29 Mar 2014 19:02:08 -0400
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Xref: csiph.com comp.lang.python:69354

On 3/29/2014 2:56 PM, contact.trigon@gmail.com wrote:
> if (a, b) != (None, None):
> or
> if a != None != b:
>
> Preference? Pros? Cons? Alternatives?

if a is not None is not b
==
if a is not None and None is not b
==
if a is not None and b is not None
which is what I would write if not trying to be cute.
a < x < b is more readable as a chained comparison than the double is not.

-- 
Terry Jan Reedy