anchor.diff:  
         let pipeline =
           beforeOne
  -        >> execFocused execOne
  +        >> execFocused (maybeSequence execOne)
           >> printOne
   
         WrappedFocusedState.WrapStates
  
positive.code:       else
          None
  
      fun (printers: TestPrinters) map ->
  
        let beforeOne (name: string, test, wrappedFocusedState) =
          printers.beforeEach name
  
negative.code:             duration = TimeSpan.Zero }
          | _ ->
            next (name, test, wrappedFocusedState)
  
        /// Used to constrain parallelism for tests that cannot be run parallel
        /// with correct results, such as Expect.isFasterThan or `benchmark<..>`
        /// based tests. Note; this does not give an ordering guarantee.
        let maybeSequence next (name, test, wrappedFocusedState) =
          try
            // here Anthony
            enterLock () (*locks*) (name, test)
            next (name, test, wrappedFocusedState)
          finally
            exitLock () (*locks*) (name, test)
  
        let execOne (name: string, test: TestCode, wrappedFocusedState: WrappedFocusedState) =
          let w = System.Diagnostics.Stopwatch.StartNew()
  