On the contrary, whitespace indentation is best on the whiteboard, and is probably what inspired Python in the first place (whiteboarding in education + pseudocode). It removes the main issues with whitespace indentation (spaces being coalesced in things like HTML and parser that's overly picky about the exact number of spaces in a block). As long as you can vaguely line up a block vertically, anyone will be able to figure out what you mean on the whiteboard.