anchor.diff:   -8 --best       Use the slowest, but best, compression possible.
    -n --no-action  Do not recompress.  With --verbose, displays a list of
                    files that would be processed.
  - -p --preserve   Preserve file modification time.
    -r --recursive  Recurse into directories.
    -s --no-sync    Do not synchronize file data.  Will return faster, with
                    the potential danger to lose your files in a system crash.
  
positive.code: maintaining the existing compression as well as the existing tags.
  
  The choice is left to the user for repairing the file manually, such
  as by editing the tag file and using `metaflac` yourself, or removing
  the temporary directory altogether.  The author uses, and recommends,
  https://picard.musicbrainz.org/[MusicBrainz Picard] to retag files
  before using `reflac`.
  
negative.code: 
  == Requirements
  
  `flac` needs to be in your $PATH.  This program is normally packaged
  as “flac” by distributions.
  
  The script both depends on Bash and GNU features of other core
  utilities.  Versions of `mv`, `getopt`, `sync`, etc from other sources
  