@jokeyrhyme @nixCraft how could significant whitespace introduce invisible bugs? The entire point of it is that it's easily visible.
Only way I can think of is mixing spaces and tabs in indentation in a way that on some editors will make a block appear to have the same indent but not be treated as such, but Python 3 already thought of that:
> Indentation is rejected as inconsistent if a source file mixes tabs and spaces in a way that makes the meaning dependent on the worth of a tab in spaces; a TabError is raised in that case.