It looks like the puzzle is to find an interleaving of execution that makes sense.
Other than solving it by hand, one idea I have is to wrap around each line of code some sort of error handler that keeps trying that line until it succeeds. This should work if the puzzle has been designed so that the interleaving can be found using a "greedy" method of executing a line as soon as it becomes possible to do so. _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
