anchor.diff:                                  // two states to get the new state value.
                                   Some <| reduction.Invoke (existingState, result))
               )
  +#if DEBUG
  +        |> tap checkParallelLoopResult
  +#endif
           |> ignore
   
           // Since we know the input array isn't empty, a state value _must_ have been set.
  
positive.code:         combineWorkerResults workerResults1,
          combineWorkerResults workerResults2
  
  #endif  // #if !FX_NO_TPL_PARALLEL
  
negative.code:                                 // two states to get the new state value.
                                  Some (mapReduction.Reduce existingState result))
              )
  #if DEBUG
          |> tap checkParallelLoopResult
  #endif
          |> ignore
  
          // Since we know the input array isn't empty, a state value _must_ have been set.
  