anchor.diff:  
     gcloud-golang = buildFromGitHub {
       version = 2;
  -    date = "2016-09-06";
  -    rev = "a47b182e769f5e75f5fc927ff6ee2678f7f552cf";
  +    date = "2016-09-12";
  +    rev = "a269f2d160169f9263253a498878cc0d37710fe9";
       owner = "GoogleCloudPlatform";
       repo = "gcloud-golang";
  -    sha256 = "0n3791sfcigpaamhh9vx34wqzch3llapsr0j1f648l67qk6s68hk";
  +    sha256 = "0scr3xwk2156pgix2f6iqv6h0mm7vdk5671jixwri7xwzc7h8g7y";
       goPackagePath = "cloud.google.com/go";
       goPackageAliases = [
         "google.golang.org/cloud"
  
positive.code:   };
  
    yaml_v2 = buildFromGitHub {
      version = 1;
      rev = "e4d366fc3c7938e2958e662b4258c7a89e1f0e3e";
      date = "2016-07-15";
      owner = "go-yaml";
      repo = "yaml";
      sha256 = "13dkg0x8ydrcc62w7j5sh6iq2wr79rqb31ks4saq5sllphr2xn7r";
      goPackagePath = "gopkg.in/yaml.v2";
    };
  
  
negative.code: 
    grpc = buildFromGitHub {
      version = 2;
      rev = "3e1c91c1e0a72a34f68542bc029792b031835cbf";
      owner = "grpc";
      repo = "grpc-go";
      sha256 = "0zm4jf04gqdf4m97y0h3gz1fn0smmabfn6b3nhkhifazyfpwgzcf";
      goPackagePath = "google.golang.org/grpc";
      goPackageAliases = [ "github.com/grpc/grpc-go" ];
      propagatedBuildInputs = [ http2 net protobuf oauth2 glog ];
      excludedPackages = "\\(test\\|benchmark\\)";
      meta.useUnstable = true;
      date = "2016-09-12";
    };
  
    gucumber = buildFromGitHub {
  