anchor.diff:  
     utp = buildFromGitHub {
       version = 2;
  -    rev = "fa8b6bbd0386e3b98845c5d1f10148b29915d4b9";
  +    rev = "cb02a8a1ac94501fb8421531cd94d874360d35b1";
       owner  = "anacrolix";
       repo   = "utp";
  -    sha256 = "1h5sbkvn8rrvhvibc0903giayvp7na2vy3xqq53kcd8d8i1n3ig8";
  -    date = "2016-10-26";
  +    sha256 = "0cx70k83bccd1kxrwf3v957hhc3pr0dxzdym15bxdkylkrmg6jwk";
  +    date = "2016-12-20";
       propagatedBuildInputs = [
         envpprof
         missinggo
  
positive.code: 
    tools = buildFromGitHub {
      version = 2;
      rev = "dd796641777bce15ee87fb6bea64943b648bdcf3";
      date = "2016-12-14";
      owner = "golang";
      repo = "tools";
      sha256 = "1hc211absrwj54wkczw57d19s2zmp262pxrrndg59k5cpk6xiynv";
      goPackagePath = "golang.org/x/tools";
      goPackageAliases = [ "code.google.com/p/go.tools" ];
  
  
negative.code: 
    ipfs = buildFromGitHub {
      version = 2;
      date = "2016-12-21";
      rev = "99d72c27818353eb2b9c05710a9a8eba87518323";
      owner = "ipfs";
      repo = "go-ipfs";
      sha256 = "0bq6ci1gbld1f2h4wdxppw74pzr73z8c9digqz199ilj4qakkdyi";
      gxSha256 = "0qg7yrjjski84wp9apzhd25v3ljkgxg1vl1hm6xnb392pnxx9qiw";
      subPackages = [
        "cmd/ipfs"
        "cmd/ipfswatch"
  