anchor.diff:  { stdenv
   , cmake
   , fetchgit
  -, ninja
   , perl
   , pythonPackages
   , python2Packages
  
positive.code:     version = fetchVersion;
    };
  
  
    nativeBuildInputs = [
      cmake
      #ninja
      perl
      pythonPackages.sphinx
      python2Packages.python
      python3Packages.cython
      python3Packages.python
      yasm
  
negative.code: }:
  
  let
    inherit (stdenv.lib)
      replaceChars;
  
    inherit ((import ./sources.nix)."${channel}")
      fetchVersion
      rev
  