anchor.diff:  
     google-cloud-go = buildFromGitHub {
       version = 3;
  -    date = "2017-06-01";
  -    rev = "d59fc17b56f5a7a34cbbc3ccfbc9880e0ee0457e";
  +    date = "2017-06-06";
  +    rev = "024c342844640b8318802e1f67950c533c0d85dd";
       owner = "GoogleCloudPlatform";
       repo = "google-cloud-go";
  -    sha256 = "1y0gr3njps61kbh5ggk8235cwyclcw4pk7ba1ldywmh520n4h4a2";
  +    sha256 = "1szy4c0ma9984hgvrpcyifil8v3aa9yx4f4l49glbvf247zn486q";
       goPackagePath = "cloud.google.com/go";
       goPackageAliases = [
         "google.golang.org/cloud"
  
positive.code:       inherit
          goPackagePath
          rev;
        date = "2017-05-31";
      };
      rev = "8e09a3d939255ba9bfb76049b7cc413740986c03";
      goPackagePath = "google.golang.org/api";
      src = fetchzip {
        version = 3;
  
negative.code: 
    net = buildFromGitHub {
      version = 3;
      rev = "59a0b19b5533c7977ddeb86b017bf507ed407b12";
      date = "2017-06-05";
      owner  = "golang";
      repo   = "net";
      sha256 = "0dq7yg1y9ni4wc4bqfk5481cjal87a01vd4jmv2khvz1n905zm8r";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "github.com/hashicorp/go.net"
  