anchor.diff:  , libwebp
   , openexr
   , pkg-config
  +, zlib
  +, buildDocs ? true
  +, asciidoc
  +, graphviz
  +, doxygen
   , python3
  -, zlib
   }:
   
   stdenv.mkDerivation rec {
  
positive.code: { stdenv, lib, fetchFromGitHub
  , fetchpatch
  , asciidoc
  , brotli
  , cmake
  , graphviz
  , doxygen
  , giflib
  , gperftools
  , gtest
  
negative.code:   ];
  
    nativeBuildInputs = [
      cmake
      gtest
      pkg-config
    ] ++ lib.optionals buildDocs [
      asciidoc
      graphviz
      doxygen
      python3
    ];
  
    # Functionality not currently provided by this package
  