Hm; I stand corrected then. Thanks, guys, especially for pointing out the car exhaust and other things. All of those things are true (about additional time to be talked out, etc). I was coming from the perspective of someone who followed Sir Terry Pratchett's campaign for legal suicide in response to things like Alzheimer's, where it isn't the kind of thing one is likely to be talked out of. In that case, of course, people are campaigning for legal euthanasia, so it's a bit different.