anchor.diff:              | 0 -> stop()
               | _ -> ()
   
  +        /// Run a function on a machine with a context and scope.
           let runOnce token (fsm: Machine<'c>) f =
               match loop with
               | Running(loop, wakeup, memory) -> let scope = Scope(token, loop, wakeup, memory)
  
positive.code: 
              | Closed ->                          ()
  
          let remove token =
              let machine = Map.find token machines
              (machine :> IDisposable).Dispose()
  
negative.code:         let mutable machines:
              Map<int64, Machine<'c>> =   Map.empty
  
          /// Stop the loop.
          /// 
          /// This will only succeed when there are no active or referenced handles.
          let stop () =
              match loop with
              | Running(handle, wakeup, memory) -> handle.Stop()
  