anchor.diff:  
   buildPythonPackage rec {
     pname = "tensorflow-tensorboard";
  -  version = "1.15.0";
  +  version = "2.1.0";
     format = "wheel";
   
     src = fetchPypi ({
  
positive.code:     markdown
      grpcio
      absl-py
      # not declared in install_requires, but used at runtime
      # https://github.com/NixOS/nixpkgs/issues/73840
      wheel
  
negative.code: , markdown
  , futures
  , absl-py
  , google-auth-oauthlib
  }:
  
  # tensorflow/tensorboard is built from a downloaded wheel, because
  