Well, it doesn't even require it - if you want to you can put the entire block on a single line ;-)

I don't mind Pythons whitespace rules at all. It's not that coding in Python requires any change to the whitespace practises I've been coding with for decades. (Well, except for one minor thing. With my editor, it's slightly easier to close a block using Perl (or C) than in Python. When coding Perl, if I start a line with a closing parenthesis, brace or bracket, it will automatically align it with the line that has the corresponding opening brace - when using Python, I have to use ^D. Same amount of keystrokes, but a lesser used combination than }, so slightly (very, very slightly) more difficult in Python than in Perl. Oh, and there's '%' (vi users will know)).