anchor.diff:  SET exit_code=%ERRORLEVEL%
   
   REM The VM exits with code 253 if the snapshot version is out-of-date.
  -IF /I "%exit_code%" EQU "253" (
  +IF "%exit_code%" EQU "253" (
     CALL "%dart%" --snapshot="%snapshot_path%" --packages="%flutter_tools_dir%\.packages" "%script_path%"
  +  SET exit_code=%ERRORLEVEL%
  +  IF "%exit_code%" EQU "253" (
  +    ECHO Error: Unable to create dart snapshot for flutter tool.
  +    EXIT /B %exit_code%
  +  )
     CALL "%dart%" %FLUTTER_TOOL_ARGS% "%snapshot_path%" %*
     SET exit_code=%ERRORLEVEL%
   )
  
positive.code:   :do_sdk_update_and_snapshot
      ECHO Checking Dart SDK version...
      CALL PowerShell.exe -ExecutionPolicy Bypass -Command "& '%FLUTTER_ROOT%/bin/internal/update_dart_sdk.ps1'"
      SET exit_code=%ERRORLEVEL%
      IF %exit_code% NEQ 0 (
        ECHO Error: Unable to update Dart SDK. Retrying... Press Ctrl+C to abort.
        GOTO :do_sdk_update_and_snapshot
      )
  
  
negative.code: 
      REM Makes changes to PUB_ENVIRONMENT only visible to commands within SETLOCAL/ENDLOCAL
      SETLOCAL
        IF "%TRAVIS%" == "true" GOTO on_bot
        IF "%BOT%" == "true" GOTO on_bot
        IF "%CONTINUOUS_INTEGRATION%" == "true" GOTO on_bot
        IF "%CHROME_HEADLESS%" == "1" GOTO on_bot
        IF "%APPVEYOR%" == "true" GOTO on_bot
        IF "%CI%" == "true" GOTO on_bot
        GOTO not_on_bot
        :on_bot
          SET PUB_ENVIRONMENT=%PUB_ENVIRONMENT%:flutter_bot
        :not_on_bot
        SET PUB_ENVIRONMENT=%PUB_ENVIRONMENT%:flutter_install
        :retry_pub_upgrade
        CALL "%pub%" upgrade --verbosity=error --no-packages-dir
        IF "%ERRORLEVEL%" NEQ "0" (
          ECHO Error: Unable to 'pub upgrade' flutter tool. Retrying...
          timeout /t 5 /nobreak
          GOTO :retry_pub_upgrade
        )
      ENDLOCAL
  
      POPD
  
      :retry_dart_snapshot
      CALL "%dart%" --snapshot="%snapshot_path%" --packages="%flutter_tools_dir%\.packages" "%script_path%"
      IF "%ERRORLEVEL%" NEQ "0" (
        ECHO Error: Unable to create dart snapshot for flutter tool. Retrying...
        timeout /t 5 /nobreak
        GOTO :retry_dart_snapshot
      )
      >"%stamp_path%" ECHO %revision%
  
    REM Exit Subroutine
  