anchor.diff:  , fetchFromBitbucket
   , fetchurl
   , lib
  +, nasm
   , ninja
   , yasm
   
  
positive.code:   nativeBuildInputs = [
      cmake
      ninja
      yasm
    ];
  
    buildInputs = [
      libx265-10
  
negative.code:     nativeBuildInputs = [
        cmake
        ninja
      ] ++ (
        if (channel == "head") then [
          nasm
        ] else [
          yasm  # Remove for > 2.6
        ]
      );
  
      buildInputs = optionals (elem targetSystem platforms.linux) [
        numactl
  