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Date: Fri, 14 Jun 2013 11:28:37 -0600
From: Michael Torrie <torriem@gmail.com>
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Subject: Re: Eval of expr with 'or' and 'and' within
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Xref: csiph.com comp.lang.python:48193

On 06/14/2013 10:49 AM, Steven D'Aprano wrote:
> Correct. In Python, all boolean expressions are duck-typed: they aren't 
> restricted to True and False, but to any "true-ish" and "false-ish" 
> value, or as the Javascript people call them, truthy and falsey values.
> <snip>
> There are a couple of anomalies -- the timestamp representing midnight is 
> falsey, because it is implemented as a zero number of seconds; also 
> exhausted iterators and generators ought to be considered falsey, since 
> they are empty, but because they don't know they are empty until called, 
> they are actually treated as truthy. But otherwise, the model is very 
> clean.

Good explanation! Definitely enlightened me.  Thank you.