anchor.diff:                    | None    -> Parsed Instant.MinValue
   
     let AcceptExtractor = fun(request:HttpRequest) ->
  -    request.headers
  -    |> Seq.filter (fun (k, v) -> k = "accept")
  -    |> Seq.map (fun (k, v) -> v)
  -    |> Seq.head
  -    |> fun x -> x.Split [|';'|]
  -    |> Seq.fold(fun acc elem -> match acc with
  +    let findFormat (x: string) =
  +        x.Split [|';'|]
  +        |> Seq.fold(fun acc elem -> match acc with
                                    | Some(r) -> Some(r)
                                    | _       -> match elem with
                                                 | "text/json" -> Some(Json)
                                                 | "text/csv"  -> Some(Csv)
                                                 | "text/xml"  -> Some(Xml)
                                                 | _           -> None) None
  +    request.headers
  +    |> Seq.filter (fun (k, v) -> k = "accept")
  +    |> Seq.map (fun (k, v) -> v)
  +    |> Seq.tryHead
  +    |> Option.bind findFormat
       |> function
         | Some(f) -> f
         | _       -> Json
  
positive.code:               return (operations, l) |> FormatPicker(f) |> OK >=> MimeType(f)
              })))
               
          NOT_FOUND "Route not found ¯\_(ツ)_/¯" ] >=> cors corsConfig
  
    startWebServer { 
      defaultConfig with 
  
negative.code:            shopppingLists:Func<IDictionary<string, List<Tuple<Blueprint, int>>>>,
             changeShoppingList:Action<string, Blueprint, int>) =
    
    let corsConfig = {
      defaultCORSConfig with
        allowedUris = InclusiveOption.Some [ "http://localhost:" + (port |> string) ]
    }
    let JsonConfig = fun lang -> 
      let settings = new JsonSerializerSettings (ContractResolver = new LocalizedContractResolver(translator, lang))
      settings.Converters.Add(new LocalizedJsonConverter(translator, lang))
  