anchor.diff:      owner = "gflags";
       repo = "gflags";
       rev = "v${version}";
  -    sha256 = "7564048256b5149b9591b37d3e63cfc675f0050dfc4ec661030a8edc493d68c5";
  +    sha256 = "43d236421279e56eb4e86bc427b6912712a94ab33ce2618b3dc2eb5e63331432";
     };
   
     nativeBuildInputs = [
  
positive.code: { stdenv
  , cmake
  , fetchFromGitHub
  , ninja
  }:
  
  let
    version = "2.1.2";
  in
  stdenv.mkDerivation rec {
    name = "gflags-${version}";
  
negative.code:     "-DBUILD_TESTING=OFF"
    ];
  
    meta = with lib; {
      description = "A C++ library that implements commandline flags processing";
      homepage = https://code.google.com/p/gflags/;
      license = licenses.bsd3;
  