what does := means simply?

Thu May 17 08:56:32 EDT 2018

On 17-05-18 03:44, Chris Angelico wrote:
> On Thu, May 17, 2018 at 11:33 AM, Abdur-Rahmaan Janhangeer
> <arj.python at gmail.com> wrote:
>> what does := proposes to do?
>>>> pep572
>>> If you read the PEP, you'll find an answer to your question.
>> https://www.python.org/dev/peps/pep-0572/
>> ChrisA

Just wondering, but in discussing this PEP has one considered
making the ';' into an expression too, with the value being
the value of the last expression?
I just ask because sometimes I have a loop that now often is written
as follows:
 while True:
 a = prepare_a()
 b = prepare_b()
 if not condition(a, b):
 break
 Do other stuff
Now with the := assignment it seems I will be able to write it like this:
 while [a := prepare_a(), b := prepare_b(), condition(a, b)][-1]:
 Do other stuff.
But IMO it would be nicer if it could be written as:
 while a := prepare_a(); b := prepare_b(); condition(a, b):
 Do other stuff
-- 
Antoon Pardon