anchor.diff:          configure (fun c -> c.AddSerializer serializer)
       
       let useSerializerFor contentType serializer =
  -        configure <| fun c -> c.AddSerializerFor contentType serializer
  +        (configure <| fun c -> c.AddSerializerFor contentType serializer)
   
  -    let logUsing logger (request:INapRequest) =
  +    let logUsing logger (request:INapRequest) : INapRequest =
           (request :?> NapRequest).ApplyConfig (
               (request :?> NapRequest).Config.SetLogging logger
           )
  +        |> fun req -> upcast req
   
   module Resp =
       let chain method url (response:NapResponse) =
  
positive.code:     /// </summary>
      /// <param name="config">The configuration to apply to the request.</param>
      /// <param name="request">The request to permute.</param>
      let applyConfiguration config (request:INapRequest) =
          (request :?> NapRequest).ApplyConfig config
      
      /// <summary>
      /// Update the configuration to use the serializer specified.
  
negative.code:     /// </summary>
      /// <param name="f">The configuration function that accepts the current configuration and outputs the new configuration.</param>
      /// <param name="request">The request to permute.</param>
      let configure f (request:INapRequest) : INapRequest =
          f (request.Advanced().Configuration)
          |> (request :?> NapRequest).ApplyConfig
          |> fun req -> upcast req
      
      /// <summary>
      /// Retrieve the configuration stored for a given request.
  