What's wrong with this code? (UnboundLocalError: local variable referenced before assignment)

[Joshua Landau]

On 24 June 2013 21:19,  <pablobarhamalzas at gmail.com> wrote:
> Thank's to you all!
>
> Setting isWhite as global worked fine.
> I'll probably be back soon with another silly question, see you then :)

By the way, it's normally bad to use globals like this. When you're
learning it's something you just do, though; it's fine for now.