anchor.diff:              this.QueueWorkItemWithTrampoline(f)
   #else
               (new Thread((fun _ -> this.Execute f |> unfake), IsBackground=true)).Start()
  -            Unchecked.defaultof<AsyncReturn>
  +            fake()
   #endif
   
   #else
           // This should be the only call to Thread.Start in this library. We must always install a trampoline.
           member __.StartThreadWithTrampoline (f : unit -> AsyncReturn) =
               (new Thread(threadStartCallbackForStartThreadWithTrampoline,IsBackground=true)).Start(f|>box)
  -            Unchecked.defaultof<AsyncReturn>
  +            fake()
   #endif
           
           /// Save the exception continuation during propagation of an exception, or prior to raising an exception
  
positive.code:             if ok then 
                  Invoke result ctxt
              else
                  Unchecked.defaultof<AsyncReturn>
  
          /// Like `CallThenInvoke` but does not do a hijack check for historical reasons (exact code compat)
          [<DebuggerHidden>]
  
negative.code:             task
  
          // Helper to attach continuation to the given task.
          [<DebuggerHidden>]
          let taskContinueWith (task : Task<'T>) (ctxt: AsyncActivation<'T>) useCcontForTaskCancellation = 
  
              let continuation (completedTask: Task<_>) : unit =
  