anchor.diff:    :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.
  +    IF "%ERRORLEVEL%" NEQ "0" (
  +      ECHO Error: Unable to update Dart SDK. Retrying...
  +      timeout /t 5 /nobreak
         GOTO :do_sdk_update_and_snapshot
       )
   
  
positive.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
      CALL "%pub%" upgrade --verbosity=error --no-packages-dir
      ENDLOCAL
  
      POPD
      CALL "%dart%" --snapshot="%snapshot_path%" --packages="%flutter_tools_dir%\.packages" "%script_path%"
      >"%stamp_path%" ECHO %revision%
  
    REM Exit Subroutine
  
negative.code: SET exit_code=%ERRORLEVEL%
  
  REM The VM exits with code 253 if the snapshot version is out-of-date.
  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%
  )
  