The text of S02, S03, and S04 still contain references to the now-defunct "statement_modifier" grammatical category.
Also, what's the reasoning behind specifically disallowing _all_ statement modifiers to "do" blocks (as opposed to forbidding just looping statement modifiers)? Is this legacy from when the distinction wasn't being made, or is there still a valid reason for forbidding conditional modifiers? Finally: when used as a statement modifier, is "given" considered to be conditional or looping? (Gut instinct: conditional.)
