anchor.diff:  
   buildPythonPackage rec {
     pname = "tensorflow-tensorboard";
  -  version = "1.11.0";
  +  version = "1.13.0";
     format = "wheel";
   
     src = fetchPypi ({
  
positive.code:     format = "wheel";
    } // (if isPy3k then {
      python = "py3";
      sha256 = "1nkd37zq9mk0gc9x6d4x8whahbx2cn0wl94lir3g1pibdzx9hc4v";
    } else {
      python = "py2";
      sha256 = "1mkyb5gn952i4s7fmc9ay4yh74ysrqbiqna6dl1qmahjpbaavbf5";
    }));
  
    propagatedBuildInputs = [ numpy werkzeug protobuf markdown grpcio ] ++ lib.optional (!isPy3k) futures;
  
    meta = with stdenv.lib; {
      description = "TensorFlow's Visualization Toolkit";
  
negative.code: , grpcio
  , markdown
  , futures
  , absl-py
  }:
  
  # tensorflow/tensorboard is built from a downloaded wheel, because
  