anchor.diff:      case os:find_executable("gzip") of
   	Name when is_list(Name) ->
   	    Z = zlib:open(),
  -	    Out = conf(data_dir,Config),
  +	    Out = get_data_dir(Config),
   	    {ok,ORIG} = file:read_file(filename:join(Out,"zipdoc")),
   	    Compressed = zlib:gzip(ORIG),
   	    GzOutFile = filename:join(Out,"out.gz"),
  
positive.code: api_deflateReset(Config) when is_list(Config) ->
      Z1 = zlib:open(),
      ?m(ok, zlib:deflateInit(Z1, default)),
      ?m(_, zlib:deflate(Z1, <<1,1,1,1,1,1,1,1,1>>, none)),
      ?m(ok, zlib:deflateReset(Z1)),
      ?m(ok, zlib:deflateReset(Z1)),
      %% FIXME how do I make this go wrong??
  
negative.code: compress_usage(Config) when is_list(Config) ->
      compress_usage(compress_usage({get_arg,Config}));
  compress_usage({get_arg,Config}) ->
      Out = get_data_dir(Config),
      {ok,C1} = file:read_file(filename:join(Out,"png-compressed.zlib")),
      {run,C1};
  compress_usage({run,C1}) ->
  