anchor.diff:          |> async.Return
   
   /// Filters an incoming HTTP request based on the beginning of the request path (case insensitive).
  -let routeStartsWithCi (subPath : string) =
  +let routeStartsWithCi (subPath : string) : HttpHandler =
       fun (ctx : HttpContext) ->
           if (getPath ctx).StartsWith(subPath, StringComparison.CurrentCultureIgnoreCase)
           then Some ctx
  
positive.code:         responseObj
  
  ///Redirects to a different location with a 302 or 301 (when permanent) HTTP status code.
  let redirectTo (permanent : bool) (location : string)  =
      fun (ctx:HttpContext) ->
          ctx.Response.Redirect(location, permanent)
          ctx |> Some |> async.Return
negative.code: 
  /// Filters an incoming HTTP request based on the accepted
  /// mime types of the client.
  let mustAccept (mimeTypes : string list) : HttpHandler =
      fun (ctx : HttpContext) ->
          let headers = ctx.Request.GetTypedHeaders()
          headers.Accept
  