anchor.diff:  
     btree = buildFromGitHub {
       version = 2;
  -    rev = "925471ac9e2131377a91e1595defec898166fe49";
  +    rev = "0c3044bc8bada22db67b93f5760fe3f05d6a5c25";
       owner  = "google";
       repo   = "btree";
  -    sha256 = "13j2c46rzbl6zdyiwg4ddgpgfan31y20x0dy2zc93809cvdsfy3l";
  -    date = "2016-10-05";
  +    sha256 = "0r89gr9ksbq4ic5valzyg8vmhi5vgjlyp8raq28lqg1ag46yph5v";
  +    date = "2016-12-11";
     };
   
     bufio_v1 = buildFromGitHub {
  
positive.code: 
    net = buildFromGitHub {
      version = 2;
      rev = "b1a2d6e8c8b5fc8f601ead62536f02a8e1b6217d";
      date = "2016-12-10";
      owner  = "golang";
      repo   = "net";
      sha256 = "0cjlvrpf3hr5y6124irbkhy978nmfdlnrddq4xprsybgwgdahd24";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "github.com/hashicorp/go.net"
  
negative.code: 
    ipfs = buildFromGitHub {
      version = 2;
      date = "2016-12-12";
      rev = "4cb236caa490270cc1c0b49f26396fa40cf0fefd";
      owner = "ipfs";
      repo = "go-ipfs";
      sha256 = "1fkg75yqi3xfvm8a92hwgx8awp3ciqjf1w9kn5zk29slqxil86dc";
      gxSha256 = "0kb16f0xgznxdq7lbhyik2rir39l5zyqh0dcic2x7fg2fd64dks6";
      subPackages = [
        "cmd/ipfs"
        "cmd/ipfswatch"
  