anchor.diff:                    assertionResults
                     |> NonEmptyList.toList
                     |> AssertionResult.List.onlyNotPassed
  -                let watch = Stopwatch()
  +                let watch = Stopwatch.StartNew()
                   try
                     match notPassed with
                     | [] -> failwith "oops!"
                     | head::tail ->
                         assert (typeof<'T> = typeof<unit>)
  -                      watch.Start()
                         // continue the test!
                         let testRes = (rest Unchecked.defaultof<'T>).Run()
                         testRes
  
positive.code:           fun () ->
              match x.Run() with
              | Done (meta, (Passed value, []), duration) ->
                  let watch = Stopwatch()
                  watch.Start()
                  try (rest value).Run()
                  with e ->
                    watch.Stop()
  
negative.code:   member __.Parameters = metadata.Parameters
    /// Execute the test.
    member __.Run() = 
      let watch = Stopwatch.StartNew()
      let result = body ()
      watch.Stop()
      match result with
  