(coro-run co (? arg #n))
  co: a coro
  arg: any type (optional)
  returns any type

Resumes a paused coroutine.

The co argument must be either newborn or paused. The coroutine will run until it yields, returns, or triggers an error.

If the coroutine was paused, then arg will be returned from the corresponding yield form. If the coroutine was newborn, then arg must be absent.

coro-run returns the value passed to yield, or the return value of the coroutine function.