anchor.diff:  
   if not "%FLAG%" == "" (
     if "%FLAG%" == "-prefix_dirs" (
  +    set "FLAG_VALUE_PREFIX_DIRS=%~2"
       shift
  -    call set "FLAG_VALUE_PREFIX_DIRS=%%~1"
       shift
     ) else if "%FLAG%" == "-suffix_names" (
  +    set "FLAG_VALUE_SUFFIX_NAMES=%~2"
       shift
  -    call set "FLAG_VALUE_SUFFIX_NAMES=%%~1"
       shift
     ) else (
       echo.%?~nx0%: error: invalid flag: %FLAG%
  
positive.code: rem
  rem Examples:
  rem   1. mkdir "c:\Python36\Lib\site-packages.pycache_copy"
  rem      copy_pycache.bat "c:\Python36\Lib\site-packages" "c:\Python36\Lib\site-packages.pycache_copy"
  rem   2. mkdir "c:\Python36\Lib\site-packages.pycache_copy"
  rem      copy_pycache.bat -prefix_dirs "__pycache__|__pycache__/37" -suffix_names ".cpython-37" "c:\Python36\Lib\site-packages" "c:\Python36\Lib\site-packages.pycache_copy"
  rem   3. mkdir "c:\Python36\Lib\site-packages.pycache_copy"
  rem      copy_pycache.bat -prefix_dirs "" -suffix_names "" "c:\Python36\Lib\site-packages" "c:\Python36\Lib\site-packages.pycache_copy"
  rem
  
  setlocal
  
negative.code: 
  rem script flags
  set "FLAG_VALUE_PREFIX_DIRS=__pycache__"
  rem default list of suffixes
  set "FLAG_VALUE_SUFFIX_NAMES=.cpython-39|.cpython-38|.cpython-37|.cpython-36|.cpython-35|.cpython-34|.cpython-33|.cpython-32|.cpython-31|.cpython-30"
  
  :FLAGS_LOOP
  
  