A future that can escape the local scope.
type EscapingFuture<E: Movable & Deinitializable>: Deinitializable, Movable
typealias Result = Int
var frame: PointerToMutable<SpawnFrame<E>>
fun await() -> Result { sink }
Awaits the result of the computation.
init(_ f: sink [E] () let -> Int)
Initializes self with f, and spawns the computation.
