Hah! Assuming the lexer doesn't choke on that, then (totally coincidentally) the do-end block will 'win' and the curly brackets block will be ignored. I could either (a) add specs making this explicit, (b) make the curly-brace block 'win' instead and add specs for that, or make sure both blocks are always called (and, obviously, add a spec for that). Happy to go with whatever here!