anchor.diff:      version = 6;
       owner = "elves";
       repo = "elvish";
  -    rev = "a13c7c2a51cd7b096401c52a617523b3192fc77c";
  -    sha256 = "0y89qc60ks8wn7mhrhlblkprm8yflz5ndyda8j9wkksrsw2p2pvn";
  +    rev = "0f1bf8cf10775bc3a9d6523a5448bee712cf2d4c";
  +    sha256 = "005axp7zdrwfr23j5lz8r0gcrvcgr11cryvifvx8fzsp45j6fair";
       propagatedBuildInputs = [
         bolt
         go-isatty
  
positive.code:       sys
      ];
      meta.useUnstable = true;
      date = "2018-03-20";
    };
  
    eme = buildFromGitHub {
  
negative.code: 
    sys = buildFromGitHub {
      version = 6;
      rev = "13d03a9a82fba647c21a0ef8fba44a795d0f0835";
      date = "2018-03-26";
      owner  = "golang";
      repo   = "sys";
      sha256 = "0ibj051npxdyny8c69h08s28zc10a2gpjzxzj8z15hqb8f29rzm1";
      goPackagePath = "golang.org/x/sys";
    };
  
  