(0.8.0)
parallel\Future::value — Resolution
Shall return (and if necessary wait for) return from task
Shall throw parallel\Future\Error if waiting failed (internal error).
Shall throw parallel\Future\Error\Killed if parallel\Runtime executing task was killed.
Shall throw parallel\Future\Error\Cancelled if task was cancelled.
Shall throw parallel\Future\Error\Foreign if task raised an unrecognized uncaught exception.
Shall rethrow Throwable uncaught in task