http://cnzsdk4ndmkx44buqh6ucvqwb6jqmr5gk46pcrmtja6a2w5zwrm74wad.onion/w/lua.html
i understand why do-while on its own isn't possible, since it wouldn't work
within the grammar (`do ... end` blocks already exist, so `while` would be
interpreted as the start of a new statement within the block rather than the end
of the block), but using `until` here is bizarre. i don't think including this
syntax at all makes much sense, there's very few times where you'd use this over
a regular `while` loop. nil keys in tables are disallowed (i.e.