"The type of concurrency used when logical threads are created is
determined by the Scheduler selected at initialization time. The
default behavior is currently to create a new kernel thread per
call to spawn, but other schedulers are available that multiplex
fibers across the main thread or use some combination of the two
approaches" (с) dlang docs
Am I right understand that `concurrency` is just wrapper that
hide implementation of tasks and fibers? So programmer can work
with threads like with fibers and vice versa?
If yes, does it's mean that spawns is planing not but with system
Scheduler, but with DRuntime Scheduler (or how it's can be
named?) and all of them work in user-space?
