anchor.diff:        # include security vulnerabilities. So we make it optional.
         # https://github.com/tensorflow/tensorflow/issues/20280#issuecomment-400230560
         sed -i '/tensorboard >=/d' tensorflow/tools/pip_package/setup.py
  +
  +      substituteInPlace tensorflow/tools/pip_package/setup.py \
  +        --replace "numpy >= 1.16.0, < 1.19.0" "numpy >= 1.16.0"
       '';
   
       preConfigure = let
  
positive.code: 
        # cudaSupport causes fetch of ncclArchive, resulting in different hashes
        sha256 = if cudaSupport then
          "09j57w6kc0vkfcdwr0qggy3qgrgq82kfa2jrwvvcnij4bl3wj40j"
        else
          "14g8z49qz7d8n1c2mcsfhr7yqpcy7mhmpm6hgmqvpgb8vm7yvwrc";
      };
  
      buildAttrs = {
  
negative.code: 
    tfFeature = x: if x then "1" else "0";
  
    version = "1.15.4";
    variant = if cudaSupport then "-gpu" else "";
    pname = "tensorflow${variant}";
  
  