anchor.diff:        then file.source
         else builtins.path { path = file.source; name = sourceName; };
   
  -  # A symbolic link whose target path matches this pattern will be
  -  # considered part of a Home Manager generation.
  -  homeFilePattern = "${builtins.storeDir}/*-home-manager-files/*";
  -
   in
   
   {
  
positive.code:         cleanup = pkgs.writeText "cleanup" ''
            . ${./lib-bash/color-echo.sh}
  
            newGenFiles="$1"
            shift 1
            for relativePath in "$@" ; do
              targetPath="$HOME/$relativePath"
              if [[ -e "$newGenFiles/$relativePath" ]] ; then
                $VERBOSE_ECHO "Checking $targetPath: exists"
              elif [[ ! "$(readlink "$targetPath")" == ${homeFilePattern} ]] ; then
                warnEcho "Path '$targetPath' not link into Home Manager generation. Skipping delete."
              else
                $VERBOSE_ECHO "Checking $targetPath: gone (deleting)"
  
negative.code:         check = pkgs.writeText "check" ''
            . ${./lib-bash/color-echo.sh}
  
            # A symbolic link whose target path matches this pattern will be
            # considered part of a Home Manager generation.
            homeFilePattern="$(readlink -e "${builtins.storeDir}")/*-home-manager-files/*"
  
            newGenFiles="$1"
            shift
            for sourcePath in "$@" ; do
              relativePath="''${sourcePath#$newGenFiles/}"
              targetPath="$HOME/$relativePath"
              if [[ -e "$targetPath" \
                  && ! "$(readlink "$targetPath")" == $homeFilePattern ]] ; then
                if [[ ! -L "$targetPath" && -n "$HOME_MANAGER_BACKUP_EXT" ]] ; then
                  backup="$targetPath.$HOME_MANAGER_BACKUP_EXT"
                  if [[ -e "$backup" ]]; then
  