anchor.diff:        echo "error: Fetched patch file '$out' is empty!" 1>&2
         exit 1
       fi
  -    "${patchutils}/bin/lsdiff" "$out" \
  +    "${buildPackages.patchutils}/bin/lsdiff" "$out" \
         | sort -u | sed -e 's/[*?]/\\&/g' \
         | xargs -I{} \
  -        "${patchutils}/bin/filterdiff" \
  +        "${buildPackages.patchutils}/bin/filterdiff" \
           --include={} \
           --strip=${toString stripLen} \
           ${lib.optionalString (extraPrefix != null) ''
  
positive.code: # often change with updating of git or cgit.
  # stripLen acts as the -p parameter when applying a patch.
  
  { lib, fetchurl, patchutils }:
  { stripLen ? 0, extraPrefix ? null, excludes ? [], includes ? [], revert ? false, ... }@args:
  
  fetchurl ({
  
negative.code:       cat "$out" 1>&2
        exit 1
      fi
      ${buildPackages.patchutils}/bin/filterdiff \
        -p1 \
        ${builtins.toString (builtins.map (x: "-x ${lib.escapeShellArg x}") excludes)} \
        ${builtins.toString (builtins.map (x: "-i ${lib.escapeShellArg x}") includes)} \
  