anchor.diff:          member x.Serialize(body : obj, stream : Stream) : unit = 
               use writer = new StreamWriter(stream)
               Jil.JSON.Serialize(body, writer, options)
  -            writer.Flush()
  +        
  +        member x.Serialize(body : obj, context : IOwinContext) = 
  +            use writer = new StreamWriter(context.Response.Body)
  +            Jil.JSON.Serialize(body, writer, options)
           
           member x.SupportedHeaders() : string [] = 
               [| "application/json"; "text/json"; "application/json;charset=utf-8"; "application/json; charset=utf-8" |]
  
positive.code:     let options = YamlDotNet.Serialization.SerializationOptions.EmitDefaults
      let serializer = new YamlDotNet.Serialization.Serializer(options)
      let deserializer = new YamlDotNet.Serialization.Deserializer(ignoreUnmatched = true)
      interface IFormatter with
          
          member x.SerializeToString(body : obj) = 
  
negative.code: // ----------------------------------------------------------------------------
  namespace FlexSearch.Core
  
  open Microsoft.Owin
  open Newtonsoft.Json
  open Newtonsoft.Json.Converters
  open System.IO
  
  [<Sealed>]
  type JilJsonFormatter() = 
      let options = new Jil.Options(false, false, false, Jil.DateTimeFormat.ISO8601, false)
      interface IFormatter with
          member x.SerializeToString(body : obj) = failwith "Not implemented yet"
          
  