anchor.diff:      { owner
       , repo
       , rev
  +    , multihash ? ""
       , sha256
       , version ? null
       , name ? "${repo}-${rev}"
  
positive.code:     , repo
      , id ? "${owner}/${repo}"
      , rev
      , sha256
      , version ? null
      , name ? "${repo}-${rev}"
      }:
      pkgs.fetchzip {
        inherit name sha256 version;
        url = "${host}/api/v4/projects/${lib.replaceStrings ["/"] ["%2F"] id}/"
          + "repository/archive.tar.bz2?sha=${rev}";
      };
  
negative.code:     { owner
      , repo
      , rev
      , multihash ? ""
      , sha256
      , version ? null
      , name ? "${repo}-${rev}"
  