On top of that, while we're on the topic, I don't know what happens if you jump into another continuation in the following circumstances:
1. you're inside atomic-invoke, call-w/stdout, call-w/stdin, or anything that creates context that needs to be undone on the way out. The problem is that a continuation from in here can be exited multiple times although it was entered only once.
2. similarly, you're inside protect, (equivalent to "finally" in java) - is the "after"-fn called, and if so, only once or for each re-entered continuation?
3. the continuation you jump into was originally running on another thread.
I should write tests to figure out what happens in all these cases, but if anybody knows the answers I can live with being lazy :)
