anchor.diff:  
   %% @doc returns the SSL options adequate for the project based on
   %% its configuration, including for validation of certs.
  --spec ssl_opts(string()) -> [term()].
  +-spec ssl_opts(Url) -> Res when
  +      Url :: string(),
  +      Res :: proplists:proplist().
   ssl_opts(Url) ->
       case get_ssl_config() of
           ssl_verify_enabled ->
  
positive.code:             error
      end.
  
  etag(Path) ->
      case file:read_file(Path) of
          {ok, Bin} ->
  
negative.code:             {fetch_fail, Name, Vsn}
      end.
  
  -spec cached_download(TmpDir, CachePath, Pkg, Url, ETag, State, ETagPath, UpdateETag) -> Res when
        TmpDir :: file:name(),
        CachePath :: file:name(),
        Pkg :: {pkg, Name :: binary(), Vsn :: binary(), Hash :: binary()},
        Url :: string(),
        ETag :: false | string(),
        State :: rebar_state:t(),
        ETagPath :: file:name(),
        UpdateETag :: boolean(),
        Res :: download_result().
  cached_download(TmpDir, CachePath, Pkg={pkg, Name, Vsn, _Hash}, Url, ETag, State, ETagPath, UpdateETag) ->
      case request(Url, ETag) of
          {ok, cached} ->
  