Thank you Dennis for taking the time to answer.
Yehuda

<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Virus-free.
www.avg.com
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Mon, Feb 22, 2021 at 3:21 AM Dennis Sweeney <report@bugs.python.org>
wrote:

>
> Dennis Sweeney <sweeney.dennis650@gmail.com> added the comment:
>
> If I understand correctly, changing the -1 to a -2 does not actually make
> the program "crash" -- you just only see one black circle.
>
> The reason is that range(40, 0, -2) produces 40, 38, 36, etc., all of
> which are even numbers, so rad % 2 is always 0, so col[rad % 2] is always
> "black". You could try:
>
>     for index, rad in enumerate(range(40, 0, -2)):
>         dot(5*rad, col[index % 2])
>
> In the future, I would suggest asking questions like this on
> StackOverflow, since this is not a bug in Python itself.
>
> ----------
> nosy: +Dennis Sweeney
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <https://bugs.python.org/issue43289>
> _______________________________________
>