anchor.diff:  
     protobuf = buildFromGitHub {
       version = 2;
  -    rev = "8ee79997227bf9b34611aee7946ae64735e6fd93";
  -    date = "2016-11-16";
  +    rev = "69b215d01a5606c843240eab4937eab3acee6530";
  +    date = "2017-02-17";
       owner = "golang";
       repo = "protobuf";
  -    sha256 = "12x7d1m6ryjqj4a1hvg60pgx12acvvc8997zlwfzzzmnb6dbc83q";
  +    sha256 = "0j2gnjmgzdwnh71fl5clwrkwpvq01rg8jz267d7ppsmbgfalmjlk";
       goPackagePath = "github.com/golang/protobuf";
       goPackageAliases = [
         "code.google.com/p/goprotobuf"
  
positive.code: 
    sys = buildFromGitHub {
      version = 2;
      rev = "e24f485414aeafb646f6fca458b0bf869c0880a1";
      date = "2017-02-10";
      owner  = "golang";
      repo   = "sys";
      sha256 = "0cc213v5jyxn773wdmanqzd08qhy14a890314x1hivcs6ysrw7iv";
      goPackagePath = "golang.org/x/sys";
      goPackageAliases = [
        "github.com/golang/sys"
  
negative.code:     version = 2;
      owner = "spf13";
      repo = "cobra";
      rev = "ee4055870c2d5f7ce112642377e32c9929c3bbaf";
      date = "2017-02-17";
      sha256 = "0mgd6wgpy4ap9k58wp65np24a35vx78f7q4a8v3jpiaa2qrgfnvf";
      buildInputs = [
        pflag
        viper
  