anchor.diff:  
               match rResult, sResult with
               | Choice2Of2 rErrors, Choice2Of2 sErrors ->
  -                return Choice2Of2 (rErrors @ sErrors)
  +                return Choice2Of2 (rErrors ++ sErrors)
               | (Choice2Of2 _ as err), Choice1Of2 _
               | Choice1Of2 _, (Choice2Of2 _ as err) ->
                   return err
  
positive.code:             match atLeast, atMost with
              | None, None ->
                  return
                      ["Invalid number of repetitions. Either the minimum or maximum (or both) number of repetitions must be specified."]
                      |> Choice2Of2
  
              | None, Some atMost ->
  
negative.code:                 match duplicateNameError with
                  | None -> errors
                  | Some duplicateNameError ->
                      LazyList.cons duplicateNameError errors
  
              LazyList.toArray errors
              |> Choice2Of2
  
          | Choice1Of2 processedPattern ->
  