anchor.diff:  
     cascadia = buildFromGitHub {
       version = 2;
  -    date = "2016-12-13";
  -    rev = "196d48ce4ae8cf1c8f87088d2884eca214240887";
  +    date = "2016-12-24";
  +    rev = "349dd0209470eabd9514242c688c403c0926d266";
       owner  = "andybalholm";
       repo   = "cascadia";
  -    sha256 = "0gl475vdvb1zapqd1548aia7lxc0iknwngk8jyhqa60x73chj219";
  +    sha256 = "0xhdlrsvzsv3va4in3iw9v1nz2f6n8zca98mq4swl8zwfdly2jj8";
       propagatedBuildInputs = [
         net
       ];
  
positive.code: 
    net = buildFromGitHub {
      version = 2;
      rev = "45e771701b814666a7eb299e6c7a57d0b1799e91";
      date = "2016-12-15";
      owner  = "golang";
      repo   = "net";
      sha256 = "16aw0gw5jbx23sb25jxk7v9fc9skc7nj8sj9lvx6j3c0j75ypvii";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "github.com/hashicorp/go.net"
  
negative.code: 
    goquery = buildFromGitHub {
      version = 2;
      rev = "v1.0.2";
      owner  = "PuerkitoBio";
      repo   = "goquery";
      sha256 = "1n57fwiyv1ndf5d21ns6q7i08qvwirpgrpsy9fvap3r0wnkdja59";
      propagatedBuildInputs = [
        cascadia
        net
  