Doesn't it steal control flow? More like a break point, except you define where execution continues.

I wonder if it's a compile error to have multiple conflicting COMEFROM statements, or if it's random, kind of like Go's select statement.

How awesome would it be to be able to steal the execution stack from arbitrary code; how much more awesome if it was indeterminate which of multiple conflicting COMEFROM frames received control! And if it included a state closure from the stolen frame?

Now I want this.