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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Thu, 14 May 2015 13:48:32 -0600
Subject: Re: a python pitfall
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On Thu, May 14, 2015 at 12:06 PM, Billy Earney <billy.earney@gmail.com> wrote:
> Hello friends:
>
> I saw the following example at
> http://nafiulis.me/potential-pythonic-pitfalls.html#using-mutable-default-arguments
> and did not believe the output produced and had to try it for myself....

See also https://docs.python.org/3/faq/programming.html#why-are-default-values-shared-between-objects