anchor.diff:  
     tail = buildFromGitHub {
       version = 3;
  -    rev = "a927b6857fc77f4823ab37102e948be667b92bd8";
  +    rev = "66928beff07e654d08f02f592e53aaab8df488d5";
       owner  = "hpcloud";
       repo   = "tail";
  -    sha256 = "0hldmklvcyz2scnil5arbpyz7l3djkgmdvv3lg09sq1ajky6bv9r";
  +    sha256 = "0llv0iaa2pc7pkvccj0lx3by7kmikkf8y13xa1xl9s96p24sxwqd";
       propagatedBuildInputs = [
         fsnotify_v1
         tomb_v1
       ];
  -    date = "2017-07-07";
  +    date = "2017-08-03";
     };
   
     tar-split = buildFromGitHub {
  
positive.code:     version = 3;
      owner = "VividCortex";
      repo = "ewma";
      rev = "b24eb346a94c3ba12c1da1e564dbac1b498a77ce";
      date = "2017-07-27";
      sha256 = "04z576zipzq7l3jkr4mw7jhjc84j9hncm7filxq9k7255hin5xx3";
      meta.useUnstable = true;
    };
  
  
negative.code: 
    sys = buildFromGitHub {
      version = 3;
      rev = "d8f5ea21b9295e315e612b4bcf4bedea93454d4d";
      date = "2017-08-03";
      owner  = "golang";
      repo   = "sys";
      sha256 = "1wb3qbcbraa3c5fgdk6v7y9jfzzhm0ds2q7rgasz4z9wai5gabkx";
      goPackagePath = "golang.org/x/sys";
    };
  
  