"Unless" feels like adding come-from (next to goto) to a language. A statement/flow should not change its meaning after being declared/written IMHO.

edit: My criticism is for the suffix version to be clear. Unless / else is actually cool.

`destroy_world() if $angry;` is Perl syntax. And Python has `destroy_word() if angry else live_long_and_prosper()`.

(But it's not remotely like come-from.)

P.S. in re the other response, "unless" is "if not". "until" is "while not".

wdym? "unless" is literally "while not", no come-from mechanics