anchor.diff:      member __.EvalInteraction(ctok, sourceText, scriptFileName, errorLogger) =
           use _unwind1 = ErrorLogger.PushThreadBuildPhaseUntilUnwind(ErrorLogger.BuildPhase.Interactive)
           use _unwind2 = ErrorLogger.PushErrorLoggerPhaseUntilUnwind(fun _ -> errorLogger)
  -#if FX_LCIDFROMCODEPAGE
           use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
  -#endif
           let lexbuf = UnicodeLexing.StringAsLexbuf(sourceText)
           let tokenizer = fsiStdinLexerProvider.CreateBufferLexer(scriptFileName, lexbuf, errorLogger)
           currState 
  
positive.code:       let stdinReaderThread = 
          new Thread(new ThreadStart(fun () ->
              InstallErrorLoggingOnThisThread errorLogger // FSI error logging on stdinReaderThread, e.g. parse errors.
  #if FX_LCIDFROMCODEPAGE
              use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
  #endif
              try 
                  try 
                    let initialTokenizer = fsiStdinLexerProvider.CreateStdinLexer(errorLogger)
  
negative.code:     member __.EvalExpression (ctok, sourceText, scriptFileName, errorLogger) =
          use _unwind1 = ErrorLogger.PushThreadBuildPhaseUntilUnwind(ErrorLogger.BuildPhase.Interactive)
          use _unwind2 = ErrorLogger.PushErrorLoggerPhaseUntilUnwind(fun _ -> errorLogger)
          use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
          let lexbuf = UnicodeLexing.StringAsLexbuf(sourceText)
          let tokenizer = fsiStdinLexerProvider.CreateBufferLexer(scriptFileName, lexbuf, errorLogger)
          currState 
  