I had this question: how can I get the value from the `task`,
like how I can get from the `spawnLinked`(`ownerTid.send` and
`receive`)?
I'm using a `taskPool` through `arr.parallel`, but it became
necessary to collect the progress from all tasks into one
variable.
In this case, I can't use `spawnLinked` because the worker is
mutable, I get the "Aliases to mutable thread-local data not
allowed" error.
Also, I could make a new `Thread` for each task, but I think this
is a bad idea. Also, I don't know how to send messages from child
thread to parent thread.
