anchor.diff:  
     gziphandler = buildFromGitHub {
       version = 2;
  -    date = "2016-10-24";
  -    rev = "172fbbbb329cf7e031dd3ab35766186fc2081eab";
  +    date = "2017-01-04";
  +    rev = "6710af535839f57c687b62c4c23d649f9545d885";
       owner = "NYTimes";
       repo = "gziphandler";
  -    sha256 = "1wd0n5qdprdjzpan5k22s3301vsbm28ri1m8x8dcs1b9f3z5cfxw";
  +    sha256 = "0hn17g478j31j3risscxshs2sj6rni70zvlgqkrx2kz92lw4v8f6";
     };
   
     handlers = buildFromGitHub {
  
positive.code: 
    geo = buildFromGitHub {
      version = 2;
      rev = "8052dea609ab3333f59022c79c55b12c25f12268";
      owner = "golang";
      repo = "geo";
      sha256 = "04y3dr4f1523x469yakpx4n38hnlm514diwzd3iiryjzqm3vjxfr";
      date = "2016-11-18";
    };
  
    glog = buildFromGitHub {
  
negative.code: 
    copystructure = buildFromGitHub {
      version = 2;
      date = "2017-01-06";
      rev = "fa7e5b3642ee8042df11f4aa0cbbe73a0c38a983";
      owner = "mitchellh";
      repo = "copystructure";
      sha256 = "02yc1xbnz3fa0rsiqxh22k1lc3yq19d95mmwbb37aizri7bqagwq";
      propagatedBuildInputs = [ reflectwalk ];
    };
  
  