anchor.diff:  
   buildPythonPackage rec {
     pname = "tensorflow-tensorboard";
  -  version = "1.7.0";
  +  version = "1.9.0";
     format = "wheel";
   
     src = fetchPypi ({
  
positive.code:     format = "wheel";
    } // (if isPy3k then {
      python = "py3";
      sha256 = "1aa42rl3fkpllqch09d311gk1j281qry6nn07ywgbs6j0kwr6isc";
    } else {
      python = "py2";
      sha256 = "1vcdkyvw22kpljmj4gxb8m1q54ry02iwvw54w8v8hmdigvc77a7k";
    }));
  
    propagatedBuildInputs = [ bleach_1_5_0 numpy werkzeug protobuf markdown grpcio ] ++ lib.optional (!isPy3k) futures;
  
    meta = with stdenv.lib; {
      description = "TensorFlow's Visualization Toolkit";
  
negative.code: { stdenv, lib, fetchPypi, buildPythonPackage, isPy3k
  , numpy
  , werkzeug
  , protobuf
  