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From: Terry Jan Reedy <tjreedy@udel.edu>
Subject: Re: Comparison Style
Date: Sat, 27 Apr 2013 17:40:46 -0400
References: <125c8f33-1a62-4dc0-9341-a2d8f7b58058@googlegroups.com> <CAPTjJmq6afVuQnXCyXNFV1QvYi_Pt2qT9tCmjBVUSvqOLunEhA@mail.gmail.com> <nqpjn81vrbluuegvj1ggvuhegdcvki6743@invalid.netcom.com> <mailman.1077.1366944517.3114.python-list@python.org> <roy-FE66BC.17031527042013@news.panix.com>
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On 4/27/2013 5:03 PM, Roy Smith wrote:
> In article <mailman.1077.1366944517.3114.python-list@python.org>,
>   Chris Angelico <rosuav@gmail.com> wrote:
>
>> If you switch the order of operands in that, the compiler won't help
>> you. Plus it "reads" wrong. So the convention is still
>> variable==constant.
>
> I just found a nice example of putting the constant first.  I've just
> done a whole bunch of ugly math to find some slice limits.  To make sure
> they're sane, I'm writing:
>
>          assert 5 <= i < j < original_song_count
>
> I can't think of any way to write that which would be as clean and easy
> to read.

Chained comparisons like this are standard math notation, which is why 
Python 'does the right thing' with them.