Script py3 and no bias update

[kwccoin]

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As this require python 3 and based on others, it is suggested to add this.

Also there is no update to bias which some other implementation and course may want it. Just a note. Not sure I dare to do the update bias in case there is a mistake. At least not in this pull request.

[mattm]

Hey, thank you for the work you did on this but because the blog post doesn't update the bias, I don't want to update it here. It's better to keep the two consistent.