anchor.diff:                      |> Choice1Of2
               else
                   return
  -                    ["Unicode characters may not be used in patterns unless the 'Unicode' compiler option is set."]
  +                    "Unicode characters may not be used in patterns unless the 'Unicode' compiler option is set."
  +                    |> LazyList.singleton
                       |> Choice2Of2
   
           | Pattern.CharacterSet charSet ->
  
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:             | Some atLeast, Some atMost
                  when atLeast > atMost ->
                  return
                      "Invalid number of repetitions. The lower value of the range is greater than the upper value of the range."
                      |> LazyList.singleton
                      |> Choice2Of2
  
              | Some atLeast, Some atMost ->
  