Parameter Thread_IO.1-IO
val in_thread : (unit -> 'a) -> 'a tin_thread frunsf ()in a separate thread, returning a blocking computation that will become determined once execution offis complete.
Thread_IO.1-IOval in_thread : (unit -> 'a) -> 'a tin_thread f runs f () in a separate thread, returning a blocking computation that will become determined once execution of f is complete.