anchor.diff:  
     go-multihash = buildFromGitHub {
       version = 2;
  -    rev = "6becc51c635d43eb3ab4783e1e4777c7f0e6e785";
  +    rev = "d6ebd610a180b411b34dba68aa29b651b312281a";
       owner  = "multiformats";
       repo   = "go-multihash";
  -    sha256 = "1d6xgjwxjiw5ggplskd2hxz32h3s7akf2cls3ahzk0fgkww15ycv";
  +    sha256 = "1nhqsx5jl16bs32njp56pmf95kqafn87k15pnfm6avaamwvym7r5";
       goPackageAliases = [ "github.com/jbenet/go-multihash" ];
       propagatedBuildInputs = [
         crypto
         go-base58
       ];
  -    date = "2017-01-06";
  +    date = "2017-02-01";
     };
   
     go-multipart-files = buildFromGitHub {
  
positive.code: 
    pq = buildFromGitHub {
      version = 2;
      rev = "67c3f2a8884c9b1aac5503c8d42ae4f73a93511c";
      owner  = "lib";
      repo   = "pq";
      sha256 = "08vd2pxsrnz8kdcwa8y3cm3f8mss7jr78jshlvdpijwqvajpkvs4";
      date = "2017-01-17";
    };
  
    probing = buildFromGitHub {
  
negative.code: 
    go-ipfs-api = buildFromGitHub {
      version = 2;
      rev = "8e5f622a684e7a121ae7e02e705c15d101ea7ee4";
      owner  = "ipfs";
      repo   = "go-ipfs-api";
      sha256 = "16rl40hmd897dcf5wdagsdg925f97kpvrxwm1si9bvy3fqcy7kwb";
      excludedPackages = "tests";
      propagatedBuildInputs = [
        go-floodsub
  