anchor.diff:  
     grpc = buildFromGitHub {
       version = 3;
  -    rev = "v1.6.0";
  +    rev = "v1.5.2";
       owner = "grpc";
       repo = "grpc-go";
  -    sha256 = "1hwibykd1qhrvlzw8zx8878kc4hwn81rjkza2x47wigvw7mmslc1";
  +    sha256 = "b73b1b59a78445c0e8cfbef3720ed63b61d7aded45bcf7f14aff149c084e48a7";
       goPackagePath = "google.golang.org/grpc";
       goPackageAliases = [
         "github.com/grpc/grpc-go"
  
positive.code:       "github.com/go-check/check"
      ];
      sha256 = "003qj5rpr27923bjvgd3mbgack3blw0m4izrq9plpxkha1glylz3";
    };
  
    circbuf = buildFromGitHub {
  
negative.code:     sha256 = "0vaqlmayva323hs7qyza1n7383d2ly2k0hv8p2j6jl4bid9w8jy0";
    };
  
    fnmatch = buildFromGitHub {
      version = 3;
      date = "2016-04-03";
      rev = "cbb64ac3d964b81592e64f957ad53df015803288";
      owner  = "danwakefield";
      repo   = "fnmatch";
      sha256 = "126zbs23kbv3zn5g60a2w6cdxjrhqplpn6h8rwvvhm8lss30bql6";
    };
  
    form = buildFromGitHub {
      version = 3;
      rev = "c4048f792f70d207e6d8b9c1bf52319247f202b8";
  